Scope rules and functions in C

• A scope in any programming is a part of the program where a defined variable can have access to whole the program or inside the main function or user defined function.
• Scope rule define the ability to access them in a program.
  1. Local Variable
  2. Global Variable

Local variable

• A local variable is a variable with local scope, meaning that it is not visible (hence not accessible) throughout the program.
• A local variable cannot access these to outside functions.

Example:

int sum(int a,int b)
      {
          int result;//local variable
          result=a+b;
          return result;
      }

      main()
      {
          int a,b,c;
          printf("Enter two numbers to add:");
          scanf("%d%d",&a,&b);
          c=sum(a,b);
          printf("SUM=%d",result);//cannot accees result in main
      }

Global variable

• A global variable is a variable with global scope,meaning that it is visible(hence accessible) throughout the program.
• A global variable can access these to outside functions.

      int sum(int,int);
      int result;//Global variable
      main()
      {
          int a,b,c;
          printf("Enter two numbers to add:");
          scanf("%d%d",&a,&b);
          c=sum(a,b);
          printf("SUM=%d",result);//cannot accees in main
      }

      int sum(int a,int b)
      {
          int result;//local variable
          result=a+b;
          return result;
      }

Local functions

• Functions declared within the body of another function will have a local scope.
• It cannot acess outside world.

Global functions

• Functions declared outside the body of all other function will have a local scope.
• It can acess anywhere in the program.

       int sum(int,int);
       int result;//Global variable
       main() 
       {
           int a,b,c;
           printf("Enter two numbers to add:");
           scanf("%d%d",&a,&b);
           c=sum(a,b);
           printf("SUM=%d",result);//cannot accees in main
       }

       int sum(int a,int b)
       {
           int result;//local variable
           result=a+b;
           return result;
       }