general computer science for engineers cisc 106 lecture 04 dr. john cavazos computer and information...
TRANSCRIPT
General Computer Science General Computer Science for Engineersfor Engineers
CISC 106CISC 106Lecture 04Lecture 04
Dr. John CavazosComputer and Information Sciences
09/10/2010
Course OverviewCourse Overview• Explain lab00.py on computer• Show it running. Add errors.
• Atomic data and variables• Sample Function• Function composition
Atomic Data : Numbers and Atomic Data : Numbers and StringsStrings- Numbers : floats, integers
Can use “type” to find out the data type of something.
type(5) # inttype (5.0) # float
- Strings Some examples : “hello” and ‘hello’
type(“hello”) # str
“hello” + “world” # plus symbol concatenates two strings
Atomic Data (cont’d)Atomic Data (cont’d)# Can mix and match numbers>>> 3 + 5.08.0
# Cannot mix numbers and strings“hello” + 3
# Builtin convert between typesstr(100)
int(“5”)
VariablesVariables
Concept:
A variable is a name that represents a value stored in the computer’s memory.
Copyright © 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Variables (cont’d)Variables (cont’d)
The age variable references the value 25
Copyright © 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Variables Naming RulesVariables Naming Rules
Copyright © 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Variable Naming Variable Naming ConventionsConventions
Copyright © 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Same Variables NamesSame Variables Names
Copyright © 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
circleArea functioncircleArea functiondef circleArea(radius) : “””
computes the area of a circle
radius – number return – number “””
PI = 3.1415 # constant variable (use caps) return PI * radius ** 2
assertEqual(circleArea(4), 50.264)
Now, what if we want to Now, what if we want to calculate area of a ringcalculate area of a ringA ring of two concentric circleswe can use our circleArea
function
= -
Area of a ringArea of a ringpi * (r1) ** 2 – pi * (r2) ** 2 first circle second circle
circleArea(r1) - circleArea(r2)
Note: Can create a function called ringArea that takes two parameters and calls circleArea twice!