Scope of Variable in C

Scope of Variable in C

In this tutorial, We will learn about scoping rule in C programming language.

Introduction

A scope is a region of the program, and the scope of variables refers to the area of the program where the variables can be accessed after its declaration. There is three type of variable with respect to the scope of the variable.

• Local Variables
• Global Variable
• Formal Parameter

Local Variable

Variables that are declared within the function block and can be used only within the function is called local variables.

 #include <stdio.h>  
 int main ()  
 {  
   int x,y,z; // x, y, z local variable definition   
   // actual initialization   
   x = 20;  
   y = 30;  
   z = x + y;  
   printf ("value of x = %d, y = %d and z = %d\n", x, y, z);   
   return 0;  
 }  

Global Variable

Variables that are declared outside of a function block and can be accessed inside the function is called global variables.

 #include <stdio.h>  
 int z; // global variable definition   
 int main ()  
 {  
   int x,y,z; // x, y local variable definition   
   x = 20;  
   y = 30;  
   z = x + y;  
   printf ("value of x = %d, y = %d and z = %d\n", x, y, z);   
   return 0;  
 }   

Formal Parameter 

Formal parameters are treated as local variables within a function and they take precedence over global variables

 int sum(int a, int b) {  
   printf ("value of a in sum() = %d\n", a);  
   printf ("value of b in sum() = %d\n", b);  
   return a + b;  
 }  

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