The following program shows how the values of data objects change in nested blocks:
/**
** This example shows how data objects change in nested blocks.
**/
#include <stdio.h>
int main(void)
{
int x = 1; /* Initialize x to 1 */
int y = 3;
if (y > 0)
{
int x = 2; /* Initialize x to 2 */
printf("second x = %4d\n", x);
}
printf("first x = %4d\n", x);
return(0);
}
The program produces the following output:
second x = 2
first x = 1
Two variables named x are defined in main. The first definition of x retains storage while main is running. However, because the second definition of x occurs within a nested block, printf("second x = %4d\n", x); recognizes x as the variable defined on the previous line. Because printf("first x = %4d\n", x); is not part of the nested block, x is recognized as the first definition of x.