内部块与外部块中的变量名称相同时覆盖

#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;
}