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CS 106A: Variables ReviewWednesday, May 13
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Today...
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1. What is a Variable?2. Arithmetic On Variables3. Variables and Control Flow4. Diagnostic Problem 4, Redux
Today...
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What is a Variable?Suitcases and Luggage Tags
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Variables are like baggage tags that attach to suitcases.
What is a Variable?
![Page 6: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/6.jpg)
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
What is a Variable?
![Page 7: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/7.jpg)
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
What is a Variable?
![Page 8: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/8.jpg)
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
What is a Variable?
int106
![Page 9: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/9.jpg)
What is a Variable?
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
Creates a suitcase and assigns a baggage tag to it:class_num = 106print(class_num)
int106
![Page 10: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/10.jpg)
What is a Variable?
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
Creates a suitcase and assigns a baggage tag to it:class_num = 106print(class_num)
int106
![Page 11: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/11.jpg)
What is a Variable?
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
Creates a suitcase and assigns a baggage tag to it:class_num = 106print(class_num)
int106
int106
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What is a Variable?
Variables are like baggage tags that attach to suitcases.
Doesn’t assign any baggage tags, but does use suitcases:print(106)
Creates a suitcase and assigns a baggage tag to it:class_num = 106print(class_num)
int106
int106
class_num
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Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
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Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
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Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
We need to keep track of what the user enters to use
it in the greeting.
![Page 16: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/16.jpg)
Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
We need to keep track of what the user enters to use
it in the greeting.
![Page 17: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/17.jpg)
Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
This is the problem that variables solve: they allow you to keep track of important data throughout the execution of your program.
We need to keep track of what the user enters to use
it in the greeting.
![Page 18: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/18.jpg)
Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
This is the problem that variables solve: they allow you to keep track of important data throughout the execution of your program.
We need to keep track of what the user enters to use
it in the greeting.
str"Parth"
![Page 19: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/19.jpg)
Okay, How Do I Use Them?
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
name = input("What is your name? ")print("Hiya, " + name + "! I'm Python.")
This is the problem that variables solve: they allow you to keep track of important data throughout the execution of your program.
We need to keep track of what the user enters to use
it in the greeting.
str"Parth"nam
e
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Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
Another Use: Modifying Variables
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Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
![Page 22: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/22.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
![Page 23: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/23.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
![Page 24: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/24.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
PixelR: 100
G: 200B: 30
![Page 25: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/25.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
PixelR: 100
G: 200B: 30
pixel
![Page 26: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/26.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
PixelR: 255
G: 200B: 30
pixel
![Page 27: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/27.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
PixelR: 255
G: 0B: 30
pixel
![Page 28: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/28.jpg)
Use a variable to keep track of important data in your program that you’ll need to refer to in the future.
pixel = image.get_pixel(x, y)pixel.red = 255pixel.green = 0pixel.blue = 0
Another Use: Modifying Variables
We need to hold on to the pixel...
...so that we can modify its attributes here.
PixelR: 255
G: 0B: 0
pixel
![Page 29: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/29.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
![Page 31: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/31.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 32: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/32.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 33: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/33.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 34: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/34.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 35: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/35.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 36: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/36.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 37: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/37.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 38: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/38.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 39: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/39.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 40: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/40.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 46: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/46.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 47: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/47.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens?
main() says kara is super coolmain() says parth is a unicornawesome() says kara is awesomeawesome() says parth is a unicornmain() says kara is super coolmain() says parth is a unicorn
![Page 48: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/48.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
kara?
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
kara?
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parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
kara?
Right here!
![Page 52: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/52.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
parth?
![Page 53: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/53.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
parth?
![Page 54: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/54.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
parth?
![Page 55: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/55.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
main()
parth?
Yeees….?
![Page 56: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/56.jpg)
parth = 'a unicorn'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
![Page 57: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/57.jpg)
parth = 'a unicorn'kara = 'fabulous'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens if we define a variable called kara at the top
level?
![Page 58: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/58.jpg)
parth = 'a unicorn'kara = 'fabulous'
def awesome(): kara = 'awesome' print('awesome() says kara is ' + kara) print('awesome() says parth is ' + parth)
def main(): kara = 'super cool' print('main() says kara is ' + kara) print('main() says parth is ' + parth) awesome() print('main() says kara is ' + kara) print('main() says parth is ' + parth)
Scope
What happens if we define a variable called kara at the top
level?
Nothing! Functions always check inside their own scope before they check the global
scope.
![Page 59: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/59.jpg)
Review
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1. Variables! What are they good for?The broad answer: keeping track of data (you might change the data, use the data, some combination of both, etc.)
Review
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1. Variables! What are they good for?The broad answer: keeping track of data (you might change the data, use the data, some combination of both, etc.)
2. Functions don’t share variables.See our review session on Functions, Parameters & References Review to see how we can make functions share data and talk to each other.
Review
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Review
1. Variables! What are they good for?The broad answer: keeping track of data (you might change the data, use the data, some combination of both, etc.)
2. Functions don’t share variables.See our review session on Functions, Parameters & References Review to see how we can make functions share data and talk to each other.
3. When you reference a variable, functions will resolve them in a specific order.
First it checks locally, then globally.
![Page 63: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/63.jpg)
Arithmetic On Variables
![Page 64: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/64.jpg)
You can do some cool stuff with variables!
num = 1
num *=2num = num*2
multiplies num by 2 and reassigns num to
be that product
num +=1 num = num+1
increments num by 1 and updates num to
be the new value
num **=3num = num**3
takes the value of num, puts it to the third power and stores the value in num
![Page 65: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/65.jpg)
You can do some cool stuff with strings!
name1 = "kara"name2 = "parth"name1 *=2 → "karakara"names_together = name1+ name2 → "karakaraparth"
● You can do "multiplication" and "addition" on string variables● "multiplication" will just multiply the copies of the word you have● "addition" will add some new characters to the end of your string
(this is also called concatenation)
![Page 66: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/66.jpg)
# Returns the square root of a numbermath.sqrt(2) # => 1.4142135623730951
Libraries and Arithmetic
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# Returns the square root of a numbermath.sqrt(2) # => 1.4142135623730951
# Returns a random integer from range(start, stop)random.randrange(start, stop)
Libraries and Arithmetic
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# Returns the square root of a numbermath.sqrt(2) # => 1.4142135623730951
# Returns a random integer from range(start, stop)random.randrange(start, stop)
# Returns a random float between start and stoprandom.uniform(start, stop)
Libraries and Arithmetic
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Variables and Control Flow
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Using variables with if and while
● Recall that boolean expressions will evaluate to either True or False ○ 1 < 2 → True○ 'abc' == 'def' → False
● You can use the values stored in your variables in these boolean expressions! This lets you make your code more generalizable ○ if num1 < num2:
#code
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Let's see a program!
Goal: we want to simulate a person flipping a coin. They want to get 10 heads before they stop. How can we keep track of how many tosses that takes?
1 2 3
4 5 6
7 8 9
10
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#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
Using variables in if/while
a variable that keeps track of how many heads we've landed on so far
![Page 73: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/73.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
a variable that keeps track of how many coin tosses there have been
![Page 74: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/74.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
checks to see if we've landed on enough heads yet, if not, loop again!
![Page 75: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/75.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
a variable that stores the result of our coin flip (0 for heads, 1 for tails)
![Page 76: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/76.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
incrementing the num_toss variable to keep track of our coin toss
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Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
checking to see if we landed on a heads or a tails
![Page 78: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/78.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
if we landed on heads, increment the num_heads variable!
![Page 79: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/79.jpg)
Using variables in if/while
#a program that tosses a coin until we get 10 heads and then prints how many flips it took to get those 10 headsdef simulate_coin_toss(): num_heads = 0 num_tosses = 0 while (num_heads < 10): toss = random.randrange(0,2) num_tosses+=1 if toss == 0: num_heads +=1 print("It took " + str(num_tosses) + " to get 10 heads")
print out how many tosses it took
![Page 80: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/80.jpg)
Diagnostic Problem 4
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Problem prompt:
Write a program that asks the user to enter a sequence of "non-decreasing" numbers one at a time. Numbers are non- decreasing if each number is greater than or equal to the last.
When the user enters a number which is smaller than their previously entered value, the program is over. Tell the user how long their sequence was.
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num:
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1
num1
int1
sequence_length: 0
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Asking for a nondecreasing sequence
num1
int1
sequence_length: 0
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')
Enter a sequence of non-decreasing numbers. Enter num: 1
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Asking for a nondecreasing sequence
num1
int1int2
sequence_length: 0
num2
int2
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
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Asking for a nondecreasing sequence
num1
int1int2
sequence_length: 0
num2
int2
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')
![Page 87: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/87.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
num1
int1nu
m2
int2 >=
sequence_length: 0
STOP, before asking for another number: is num2 >=
num1?
![Page 88: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/88.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
num1
int1nu
m2
int2 >=
sequence_length: 0
STOP, before asking for another number: is num2 >=
num1?
print("Enter a sequence of non-decreasing numbers.)sequence_length =0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')if num2 >= num1:
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
num1
int1nu
m2
int2 >=
sequence_length: 1
STOP, before asking for another number: is num2 >=
num1?Yes it is! So we ask for
another number and increment our counter variable
![Page 90: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/90.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2
num1
int1nu
m2
int2 >=
sequence_length: 1
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')if num2 >= num1:
sequence_length +=1
STOP, before asking for another number: is num2 >=
num1?Yes it is! So we ask for
another number and increment our counter variable
![Page 91: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/91.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num3
int3
num1
int1nu
m2
int2 >=
sequence_length: 1
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num3
int3
num1
int1nu
m2
int2 >=
sequence_length: 1
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')if num2 >= num1:
sequence_length +=1num3 = int(input('Enter a num:'))
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
RECONFIGURE
num1
int2nu
m2
int2
sequence_length: 1
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
RECONFIGURE
num1
int2nu
m2
int2
sequence_length: 1
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')if num2 >= num1:
sequence_length +=1num1 = num2
![Page 95: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/95.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num1
int2nu
m2
int3
sequence_length: 1
>=
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Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num1
int2nu
m2
int3
sequence_length: 1
>=print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')if num2 >= num1:
sequence_length +=1num1 = num2num2 = int(input('Enter a num:')
![Page 97: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/97.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num1
int2nu
m2
int3 >=
sequence_length: 2
STOP, before asking for another number: is num2 >= num1?Yes it is! So we ask for another number and increment our
counter variable
![Page 98: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/98.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3
num1
int2nu
m2
int3 >=
sequence_length: 2
STOP, before asking for another number: is num2 >= num1?Yes it is! So we ask for another number and increment our
counter variable
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')while num2 >= num1:
sequence_length +=1num1 = num2num2 = int(input('Enter a num:')
![Page 99: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/99.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3Enter num: 4Enter num: 2
num1
int4nu
m2
int2 >=
STOP, before asking for another number: is num2 >= num1?No it isn't! So we print out the ending comments
sequence_length: 3
![Page 100: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/100.jpg)
Asking for a nondecreasing sequence
Enter a sequence of non-decreasing numbers. Enter num: 1Enter num: 2Enter num: 3Enter num: 4Enter num: 2
STOP, before asking for another number: is num2 >= num1?
No it isn't! So we print out the ending comments
sequence_length: 3
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')while num2 >= num1:
sequence_length +=1num1 = num2num2 = int(input('Enter a num:')
print ( "Thanks for playing!" ) print ( "Sequence length: " + str(sequence_length))
![Page 101: CS 106A: Variables Reviewweb.stanford.edu/class/cs106a/handouts/VariablesReview.pdf · print(class_num) int 106 int 106 class_num. Okay, How Do I Use Them? Use a variable to keep](https://reader034.vdocuments.us/reader034/viewer/2022050606/5fadb95903253407d531304e/html5/thumbnails/101.jpg)
Solution
print("Enter a sequence of non-decreasing numbers.)sequence_length = 0num1 = int(input('Enter a num:')num2 = int(input('Enter a num:')while num2 >= num1:
sequence_length +=1num1 = num2num2 = int(input('Enter a num:')
print ( "Thanks for playing!" ) print ( "Sequence length: " + str(sequence_length))