1.#include<stdio.h>int main(){  int a,b,c,d;   printf("请输入三个数字，分别对应a,b,c\n");   scanf("%d%d%d",&a,&b,&c);   printf("a=%d,b=%d,c=%d\n",a,b,c);   d=c,c=b,b=a,a=d;  printf("a=%d,b=%d,c=%d\n",a,b,c);          return 0;}
2. #include<stdio.h>  int main()  {  int a,b,c;    printf("请输入X分钟\n");    scanf("%d",&a);   b=a/60;   c=a%60;   printf("%d分钟=%d小时%d分钟\n",a,b,c);   return 0;}3. #include <stdio.h>  int main(){  int a,b,c,d,e,f;    printf("请输入一个四位数字\n");    scanf("%d",&a);    b=a/1000;    c=a%1000%100%10;     d=a%1000%100/10;    e=a%1000%100%10;    f=b+c*10+d*100+e*1000;   printf("它的倒序数为%04d\n",f);   return 0;}4.#include <stdio.h>#define PI 3.1415926 int main() { float r,l,v;   printf ("请输入半径\n");  scanf ("%f",&r);   I=2*PI*r;   v=(double)4/3*PI*r*r;   printf("圆的周长为%.2f,球的体积为%.2f\n",v);   return 0;}