Function

 

C – Functions

 

 A function is a set of statements enclosed within curly brackets ({}) that take inputs do the computation and provide the resultant output.

Functions are sets of statements that take inputs, perform some operations, and produce results. The operation of a function occurs only when it is called.

Functions in C are the basic building blocks of a C program.

You can call a function multiple times, by allowing reusability and modularity in C programming.

Instead of Writing the same code for different inputs repeatedly, we can call the function instead of writing the same code over and over again.

Functions are used to perform certain actions, and they are important for reusing code: Define the code once, and use it many times.

 

Types of function

 

·      Standard library functions

·      User-defined functions

 

 

Standard library functions

The standard library functions are built-in functions in C programming. A library function is also referred to as a “built-in function”. There is a compiler package that already exists that contains these functions, each of which has a specific meaning and is included in the package.

 Built-in functions have the advantage of being directly usable without being defined, whereas user-defined functions must be declared and defined before being used.

These functions are defined in header files.

 For example,

The printf() is a standard library function to send formatted output to the screen (display output on the screen).

This function is defined in the stdio.h header file.

Hence, to use the printf()function, we need to include the stdio.h header file using #include <stdio.h>.

The sqrt() function calculates the square root of a number. The function is defined in the math.h header file. 

 

User-defined function

Functions that are created by the programmer are known as User-Defined functions.

You can also create functions as per your need. Such functions created by the user are known as user-defined functions.

User-defined functions can be improved and modified according to the need of the programmer.

we need to declare and define our own functions according to the syntax.

Basic Syntax of Functions

 

The basic syntax of functions in C programming is:

return_type function_name(arg1, arg2, … argn)

{

Body of the function //Statements to be processed

}

return type: - Declare the data type of the value returned by functions.  The keyword void indicates to the compiler that the function will not return any value.

function name: -This is the function’s name that helps the compiler identify it whenever we call it.

arg1, arg2 ...arg n: It is the argument or parameter list that contains all the parameters to be passed into the function.

The list defines the data type, sequence, and the number of parameters to be passed to the function.

A function may or may not require parameters.

Hence, the parameter list is optional.

Body: The function’s body contains all the statements to be processed and executed whenever the function is called.

 Function Declaration

The function declaration lets the compiler know the name, number of parameters, data types of parameters, and return type of a function.

Eg.

return_type function_name( parameter list );

int max(int num1, int num2);

Function Definition

It is defining the actual statements that the compiler will execute upon calling the function. Function definition must return only one value at the end of the execution.

return_type function name (parameters)

{

    //body of the function

}

Return type: The function always starts with a return type of the function. But if there is no return value then the void keyword is used as the return type of the function.

Function Name: Name of the function which should be unique.

Parameters: Values that are passed during the function call.

return type function name( parameter list )

{

   Body of the function

}

Return Type − A function may return a value. The return_type is the data type of the value the function returns. Functions perform the desired operations without returning a value. It uses keyword void.

Function Name − this is the actual name of the function. The function name and the parameter list together constitute the function signature.

Parameters − When a function is invoked, pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional.

 

Function Body − the function body contains a collection of statements that define what the function does

Function Call

 Function call is calling a function to be executed by the compiler.

You can call the function at any point in the entire program.

When a program calls a function, the program control is transferred to the called function.

A called function performs a defined task and when its return statement is executed or when its function-ending closing brace is reached, it returns the program control back to the main program.

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Milan Tomic

Hi. I’m Designer of Blog Magic. I’m CEO/Founder of ThemeXpose. I’m Creative Art Director, Web Designer, UI/UX Designer, Interaction Designer, Industrial Designer, Web Developer, Business Enthusiast, StartUp Enthusiast, Speaker, Writer and Photographer. Inspired to make things looks better.

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