Thursday, 17 October 2013

Functions in C and C++ Programming

Functions in Programming 

The functions are like subtasks. They receive some information, do some procedure and provide a result. Functions are invoked through a calling program. Calling program does not require to know what the function is doing and how it is performing its task. There is a specific function-calling methodology. The calling program calls a function by giving it some information and receives the result.
We have a main () in every C program. ‘main()’ is also a function. When we write a function, it must start with a name, parentheses, and surrounding braces just like with main(). Functions are very important in code reusing.
There are two categories of functions:
a)      Functions that return a value
b)      Functions that do not return a value
Suppose, we have a function that calculates the square of an integer such that function will return the square of the integer. Similarly we may have a function which displays some information on the screen so this function is not supposed to return any value to the calling program.
A Function Structure
The declaration syntax of a function is as follows:
Return-value-type function-name (argument-list)
            Declarations and statements

The first line is the function header and the declaration and statement part is the body of the function.

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