Explain scope of a variable in C language.

Storage classes specify the scope, lifetime and binding of variables.

To fully define a variable, one needs to mention not only its ‘type’ but also its storage class.

A variable name identifies some physical location within computer memory, where a collection of bits are allocated for storing values of variable.

Storage class tells us the following factors −

• Where the variable is stored (in memory or cpu register)?
• What will be the initial value of variable, if nothing is initialized?
• What is the scope of variable (where it can be accessed)?
• What is the life of a variable?

Scope

Scope defines the visibility of an object. It defines where an object can be accessed.

The scope variable is local or global

• The variable defined within the block has local scope. They are visible only to the block in which they are defined.
• The variable defined in global area is visible from their definition until the end of program. It is visible everywhere in program.

Example

Following is the C program for the scope of a variable −

#include<stdio.h> int c= 30; /* global area */ main ( ) {    int a = 10; //local scope//    printf ("a=%d,c=%d"a,c);    fun ( ); } fun ( ){    printf ("c=%d",c); //global variable }

Output

When the above program is executed, it produces the following output −

a =10, c = 30 c = 30

Example

Following is the C program for the local and global variables −

 Live Demo

#include<stdio.h> int a,b; a=1,b=2; main() {    int c,d;    printf("enter c and d values:");    scanf("%d%d",&c,&d);    c=c+d; //local variables    b=a*b; //global variables    printf("c value is:%d
",c);    printf("b value is:%d
",b); }

Output

When the above program is executed, it produces the following output −

enter c and d values:4 7 c value is:11 b value is:2