Detailed overview of C Language Function [Tutorial]

Functions:
Function is a set of instructions to carry out a particular task. The Function after processing returns a single value.
In other word, we say a Function is a group of statements that can perform any particular task. 

Types of functions:

There are two types of Functions in C

1. Standard Functions  (Pre-defined Functions)


2. User-defined Functions

 1. Standard functions:

All standard functions, such as sqrt() , pow() , log() , sin() etc. are porvided in the library of the functions. The standard functions are also called library functions or built in functions. Predefined Functions are already created. Eg: printf() , scanf() , getch() , clrscr() etc.

2. User defined functions:

User defined Functions which are created by the User according to his need.

Function Defination:

Defining a function means writing an actual code for a function. Suppose you are defining a function which computes the square of a given number. Then you have to write a set of instructions to do this. There are different methods to define functions. The following two ways are used in defining functions:

1. NON ANSI style


2. ANSI style

1. NON ANSI style

The general form of NON ANSI function definition is as follows:

type name_of_the_function (parameter list)

parameter definition;

{

variable declaration;

stmt 1; 

stmt2;

.......

.......

return(value_computed);

}

where

• type => The data type of the return value by the function. 

• name_of_the_function => This is a user-defined function name.

• parameter list => List of variables that recieve, the value from the calling function. 

• parameter definition => Type declaration of the variables of the parameter list.

• return => A keyword used to send the output of the function, back to the calling function. There may be one or more return statements. When return is e