C – Functions

 C – Functions

A function in C Language is an organized block of reusable code, which avoids repeating the tasks again and again. If you want to do a task repeatedly in a code, then just make a function, set the task in it, and call the function multiple times whenever you need it.

Create and call a Function

To create a function in C language, set the name of the function followed by parentheses:

void demoFunction() { // write the code }

A function in C language gets executed when it is called:




Let us now see an example to create a function:

#include <stdio.h> // Demo function void demoFunction() { printf("This is a demo function.\n"); } int main() { // Calling the function demoFunction(); return 0; }

• Output

This is a demo function.

Function Declaration and Definition

In the above example, we saw how to create and call a function. We defined and declared the function as well:

void demoFunction() { // function declaration // function body i.e. the definition }

As shown above, a function has two parts:

• Function Declaration
• Function Definition

We can also write the above function by separating function definition and declaration. Let us see an example:

#include <stdio.h> // Function Declaration void demoFunction(); int main() { // Calling the function demoFunction(); return 0; } // Function Definition void demoFunction() { printf("This is a demo function.\n"); }

Output

This is a demo function.

Function Parameters

Set the parameters in a C function after the name of the function. For example:



To call a function with a parameter, set the value of the variable while calling, for example:

demoFunction(5)

Therefore, we have passed the rank with the value 5 while calling above.

Let us now see an example:

#include <stdio.h> // Function with a parameter void detailsFunc(int rank) { printf("Rank = %d",rank); } int main() { // Calling the function detailsFunc(5); return 0; }

Output

Rank - 5

Multiple Parameters

We can also set more than one parameter in a function. For example:

void demoFunction(char player[], int rank, int points) { }

To call a function with multiple parameters, set the value of the variable while calling, for example:

demoFunction("Amit", 1, 100)


We have passed the following multiple parameters while calling above:

• player: Amit
• rank: 1
• points: 100

Let us now see an example:

#include <stdio.h> // Function with multiple parameters void detailsFunc(char player[], int rank, int points) { printf("Player = %s",player); printf("\nRank = %d",rank); printf("\nPoints = %d\n\n",points); } int main() { // Calling the function detailsFunc("Amit", 1, 100); detailsFunc("David", 2, 90); return 0; }

Output

Player = Amit Rank = 1 Points = 100 Player = David Rank = 2 Points = 90

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