C Program Structure

A C program basically has the following form:

• Preprocessor Commands
• Type definitions
• Function prototypes - declare function types and variables passed to function.
• Variables
• Functions

We must have a main() function.

A function has the form:

If the type definition is omitted C assumes that function returns an integer type. NOTE: This can be a source of problems in a program.

So returning to our first C program:

NOTE:

• C requires a semicolon at the end of every statement.
• printf is a standard C function - called from main.
• n signifies newline. Formatted output - more later.
• exit() is also a standard function that causes the program to terminate. Strictly speaking it is not needed here as it is the last line of main() and the program will terminate anyway.