C语言变量作用域

// hiding.c -- variables in blocks
#include <stdio.h>
int main()
{
    int x = 30;      // original x

    printf("x in outer block: %d at %p\n", x, &x);
    {
        int x = 77;  // new x, hides first x
        printf("x in inner block: %d at %p\n", x, &x);
    }
    printf("x in outer block: %d at %p\n", x, &x);
    while (x++ < 33) // original x
    {
        int x = 100; // new x, hides first x
        x++;
        printf("x in while loop: %d at %p\n", x, &x);
    }
    printf("x in outer block: %d at %p\n", x, &x);

    return 0;
}