Lecture #5 – Parts of your first program

Published on: Thu Feb 04 2010

Include Files - Pull what is necessary from included library’s and inserts into Binary Standard Libraries - Math and Standard Operations The Preprocessor (More on this in CSE 230) - Strips our Comments - Makes substitutions for named constants - insert definition of included function files (Reserves space for them) Every C Program must have a main function int main (void)

Execution begins and ends with the main function
Program Statements are executed sequentially
Execution begins at first statement of main
( ) are used to specific function parameters
{ } enclose the body, are used to group statements
If you do not declare int main you do not need to end with return 0;
n means “go to the next line”
backslash key is an escape character
t means tab
return 0; - Signals successful end of your program to the operating system
Many functions return values, ie: Mathematical functions

Program Structure

Preprocessor directives
1. #include-d files
2. Other definitions/Declarations
Supporting functions
Main functions

Variables are named blocks of memory Intergers Regular int = 4 bytes Short int = 2 bytes Floating Points Float = 4 bytes (standard accuracy, 8 digits after decimal) Double = 8 bytes (better accuracy, more decimals) Char – 1 byte Every memory block has a # and your var is assigned a # (by Preprocessor?)