csc 107 – programming for science. history of c dennis ritchie developed c from 1969 – 1973 ...

LECTURE 2:PROGRAMMING BASICS

CSC 107 – Programming For Science

History of C

Dennis Ritchie developed C from 1969 – 1973

Based upon B (& other) earlier languages Since its creation, language grown

organically Tradition of adding features beyond standard

as desired

History of C++

Bjarne Stroustrup created to add “objects” Also included many other improvements to

language Name is inside joke: "++" is increment

operator in C Updated for quick growth

ISO standard adopted in 1998 Recently updated to C++ 201x

C Versus C++

C++ is designed to be as compatible with C as

possible, thereby providing a

smooth transition from C

C Versus C++

C++

C

C Versus C++

C

C Versus C++

Latest definition of C added most C++ features Not classes & objects, these only found in

C++ For this reason, also not a part of CSC 107 Differences now minimal and easily

avoided Once objects removed, C++ just

“looser” C Removes annoying restrictions that had

been in C Since makes life easier, often supported in

C anyway

Computers are VERY, VERY stupid

Computers have no common-sense They will only do what you tell them to

do NOT what you want them to do, which

often differs

Computers have no common-sense They will only do what you tell them to

do NOT what you want them to do, which

often differs

Computers have no common-sense They will only do what you tell them to

do NOT what you want them to do, which

often differs

While this is true for every computer does Programming highlights exactly how this

happens As you will see, C++ does nothing to

prevent mistakes

Case-Sensitivity

Example of computers being very literal And language not helping by fixing what you

say

main, Main, & MAiN treated as totally different Case of the letters matters, not just the

words Might want difference; C++ won’t change Main to main

Can help prevent easy mistakes from swapping names

With just a little practice, becomes second nature

“Whitespace”

One (very small) way C++ actually helps you C++ treats whitespace equally – spaces,

enters, & tabs Whether 1 or 1000000000000 – all will be

ignored Cannot use in symbol, whitespace

splits words Treats these as different “: :” and “::”

Spaces between words needed, but not counted Wecansplitwordsbutthecomputercannot

“Whitespace”

One (very small) way C++ actually helps you C++ treats whitespace equally – spaces,

enters, & tabs Whether 1 or 1000000000000 – all will be

ignored Cannot use in symbol, whitespace

splits words Treats these as different “: :” and “::”

Spaces between words needed, but not counted Wecansplitwordsbutthecomputercannot

Your First C++ Program

#include <iostream>using std::cout;

int main() { /* Hi, Mom. This is a comment

that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end}

#include Statements

#include <iostream>using std::cout;

/* Hi, Mom. This is a comment that goes over 2 line. */int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end}

Nearly every C++ file begins with this directive May add more #include to include other

files Contents of included file usable as if it

were here Easy way to copy ideas across multiple

files Programs can use two types of #include

statements Include system file using #include <filename>

#include “filename” includes a file you wrote

Watch Me Pull a Rabbit

#include <iostream>using std::cout;

/* Hi, Mom. This is a comment that goes over 2 line. */int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end}

For now, automatically start each file with this line Details are unimportant – consider it

magic

Watch Me Pull a Rabbit

#include <iostream>using std::cout;

/* Hi, Mom. This is a comment that goes over 2 line. */int main() { std::cout << “Hello world!”; return 0; // This comment goes to the line’s end}

For now, automatically start each file with this line Details are unimportant – consider it

magic

Your First C++ Program

#include <iostream>using std::cout;

int main() { /* Hi, Mom. This is a comment

that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end}

main Function

#include <iostream>using std::cout;

int main() { /* Hi, Mom. This is a comment

that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end

}

All C++ programs contain function called main Tells computer where to start running

program Code inside the braces will be what is

executed For the moment, consider this more “magic”

main Function

#include <iostream>using std::cout;

int main() { /* Hi, Mom. This is a comment

that goes over 2 line. */ std::cout << “Hello world!”; return 0; // This comment goes to the line’s end

}

All C++ programs contain function called main Tells computer where to start running

program Code inside the braces will be what is

executed For the moment, consider this more “magic”

Comments

Vital for writing and maintaining any program Not required to run program - only for

human eyes Computer simply ignores anything in a

comment Use to describe code in simple English

Sie konnen auch auf Deutsch schreiben o U c%d wrte n txt msg

Should be used liberally I add comments where cannot see what

code does Impossible to have too many comments, if

readable

Comments in C++

Double slash comments continue to line’s enda = a – 4; // Hi, Mom!// This entire line is a comment!

/* … */ comments can be on one or more linesa = a - /* Hi, Mom! */ 4;/* This comment takes an entire line. *//* This is a really long comment that * goes on to multiple lines. The stars on * lines 2 and on are optional, but * makes things easier to read. */

Your Turn

Get in groups & work on following activity

For Next Lecture

Read sections 4.1 – 4.10 in book for Friday What is a data type? What are variables? How can we use variables in a program? How are literal, constant, & variable

different?

Week #1 weekly assignment due Tuesday Problems available via Angel – covered 1st

one already If problem takes more than 10 minutes,

TALK TO ME!