Function

 

Function:

Function is defined as a self contained block of statements which is written to perform a particular task. By using the functions the program code is organized into groups for action. The C program is a collection of functions. Every C program has at least one function, which is main() and the most trivial program can define additional function.

 

Uses of C Function:

 

1. C function are used to avoids rewriting the same code again and again.

 

2. A large C program can easily be tracked when it is divided into function.

 

3. We can call C function any number of time in a program and from any place in a program.

 

4. Reusability is the main achievement of C function.

 

 

C Function Aspects :

 

There are three aspects of C function 

 

 a) Function declaration : This inform compiler about the function name, function parameters and return value data types.

 

b) Function call : This call the actual function.

 

c) Function definition : This contains all the statement to executed. 

 

 

Type of Function:

 

There are two type of function in C programming 

 

1) Library Function : library function are the function which are declare in C header file such as scanf(), printf(), gets(), etc.

 

2) User-define Function : user-define function are the function which are created by C programmer, so that it can uses many time. It reduces the complexity of big program and optimize the code.

 

Ex:

output:

Function Argument :

 

While calling a function, the argument can be passed to the function in two ways, call by value and call by reference.

 

1) Call by value :

•  In call by value method, the value of variable are passed to the function as parameter.
• The value of actual parameter can not be modified by formal parameter.
• Different memory is allocated for both actual and formal parameters. Because of value of actual parameter is copied to formal parameter. 

Ex: 

2) Call by Reference :

• In the call by reference method, the address of the variable is passed to the function as parameter.
• The value of the actual parameter can be modified by formal parameter.
• Same memory is used for actual and formal parameters since only address is used by both parameters.

Ex: