#include <stdio.h>
void main()
{
??? int x, a, b, c, f, z,sum;
??? printf ("input x");
??? scanf ("%d", &x);
??? a = x / 1000;
??? f = x % 10;
??? b = (x - a * 1000) / 100;
??? c = (x - a * 1000 - b * 100) / 10;
??? z = f * 1000 + c * 100 + b * 10 + a * 1;
??? sum = a + b + c + f;
??? printf("a=%d, b=%d, c=%d, f=%d, z=%d, sum=%d",a, b, c, f, z,sum);
}

核心思想是求出四位數的各位數，再用printf進行倒著輸出