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