User-Defined Functions

Write a multifunction program to illustrate the properties of global variables.
A program to illustrates the properties of global variables is presented. Note that variables x is used in all functions but none except fun2, has a definition for x. Because x has been declared 'above' all the functions, it is available to each function without having to pass x as a function argument. Further, since the value of x is directly available, we need not use return(x) statements in fun1 and fun3. However, since fun2 has a definition of x, it returns its local value of x and therefore uses a return statement. In fun2, the global x is not visible. The local x hides its visibility here.

#include <stdio.h>
int fun1(void);
int fun2(void);
int fun3(void);
int x ;   /* global */
void main( )
   {
 x = 10 ;  /* global x */
 printf("x = %d\n", x);
 printf("x = %d\n", fun1());
 printf("x = %d\n", fun2());
 printf("x = %d\n", fun3());
 getch();
   }
   fun1(void)
   {
 return(x = x + 10);
   }
   int fun2(void)
   {
 int x ;   /* local */
 x = 1 ;
 return (x);
   }
   fun3(void)
   {
 return(x = x + 10);  /* global x */
   }

OUTPUT
x = 10
x = 20
x = 1
x = 30