Difference Between Local and Global Variables in C

In C programming language, variables defined within some function are known as Local Variables and variables which are defined outside of function block and are accessible to entire program are known as Global Variables.

This article explains the difference between local and global variables.

Local Vs. Global Variable

Those variables which are defined within some function and are accessible to that function only are called Local Variables.

Those variables which are defined outside of function block and are accessible to entire program are known as Global Variables.


Scope is local to that block or function where they are defined.

Scope is global i.e. they can be used anywhere in the program.


Default value is unpredictable (garbage).

Default value is Zero (0).


Example: 


#include<stdio.h>
void main()
{
   int x=23, y=4;
   printf(“x = %d and y=%d”,x,y);
}
Here x and y are local variables.

Example: 


#include<conio.h>
int a=10,b;
void main()
{
  printf(“a = %d and b=%d”,a,b);
}
Here a and b are global variables.