Explain scope rules related to the functions in C language

Scope rules are related to the following factors −

Accessibility of a variables.
Period of existence of a variable.
Boundary of usage of variables.

Scope rules related to functions are as follows

Function which is a self-contained block that performs a particular task.
Variables that are declared within the function body are called local variables.
These variables only exist inside the specific function that creates them. They are unknown to other functions and to the main functions too.
The existence of local variables ends when the function completes its specific task and returns to the calling point.

Example 1

Following is the C program for scope rules related to functions −

#include<stdio.h>
main ( ){
   int a=10, b = 20;
   printf ("before swapping a=%d, b=%d", a,b);
   swap (a,b);
   printf ("after swapping a=%d, b=%d", a,b);
}
swap (int a, int b){
   int c;
   c=a;
   a=b;
   b=c;
}

Output

The output is stated below −

Before swapping a=10, b=20
After swapping a = 10, b=20

Variables that are declared outside the function body are called global variables.
These variables are accessible by any of the functions.

Example 2

Here is another C program for scope rules related to functions −

include<stdio.h>
int a=10, b = 20;
main(){
   printf ("before swapping a=%d, b=%d", a,b);
   swap ( );
   printf ("after swapping a=%d, b=%d", a,b);
}
swap ( ){
   int c;
   c=a;
   a=b;
   b=c;
}

Output

The output is stated below −

Before swapping a = 10, b =20
After swapping a = 20, b = 10

Bhanu Priya

Updated on: 15-Mar-2021

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