Functions in ‘C’ Language.

Functions in ‘C’ Language.

Functions are self-contained blocks, containing statements, which perform a coherent task of some kind.

Every ‘C’ program is a collection of functions.

Functions break large computing Tasks into smaller ones.

Functions avoid the need for REDUNDANT PROGRAMMING.

Functions increases the LOGICAL CLARITY of the program.

Functions specifically makes the user to build a CUSTOMIZED LIBRARY of

frequently used routines.

Functions also promote portability of source code.

Properties:

Every ‘C’ program consists of one or more functions of which main() is

primary function.

Execution of the program always begins by carrying the instructions in

main() Function Only.

Remaining functions are subordinate to main() or may be to one

another.

For a program with multiple functions, the definitions of the functions

may appear in any order and can be independent of one another.

A function carries its intended action whenever it is accessed from

several different places within a program.

Once the function completes its intended action, control returns to the

point from where the function was accessed.

A function processes information that is passed to it from calling portion

of the program, and returns a single value.

Information is passed via arguments and value is returned through

return statement.

User defined functions:

These functions are generally designed by the programmers, to

customize their programming sequence

The user-defined functions have three properties

1) Prototype or Signature

2) Calling

3) Definition

Prototype:

The information revealed by a functions prototype is

1. Function name.

2. Data type of parameters/arguments.

3. Data type of data returned.

Calling:

The steps fallowed through calling are:

1. Control jumps to the memory where the Functions Definition is

located.

2. Function performs all the instructions provided in the definition in

a sequential manner.

3. After performing all the instructions control will move to the

Function from where it was called.

Definition:

Definition is the set of instructions that become the responsibility of the

function whenever it is called.

Syntax:

Let us Understand the Functional Process Flow.

Function Process I

Program

#include<stdio.h>

void main()

{

basic();

printf(“\nIntroduction to Functions in ‘C’.”);

}

basic()

{

printf(“\nFunction Basics.”);

return;

}

Function Process II

Program

#include<stdio.h>

void main()

{

printf("\nMain Control.");

one();

two();

three();

}

Data Type of Return Value

Function Name

( DataTypeofParameter) ;

one()

{

printf("\nFunction Ones Duty.");

}

two()

{

printf("\nSecond Functions Duty.");

}

three()

{

printf("\nThird Functions Duty.");

}

Function Process III

Program

#include<stdio.h>

void main()

{

printf("\nMain Control.");

one();

printf("\nReturn to Main Module.");

}

one()

{

printf("\nFirst Functions Duty.");

two();

printf("\nControl Returns to One.");

}

two()

{

printf("\nSecond Functions Duty.");

three();

}

three()

{

printf("\nThird Function Duty.");

}