四则运算

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 
 4 int main()
 5 {
 6     int j=0;
 7 
 8     printf("请选择四则运算的法则：\n");
 9     printf("1.加 2.减 3.乘 4.除\n");
10     int num;
11     scanf("%d",&num);
12 
13     for(int i=0;i<400;i++){
14         int a,b;
15         a = rand()%100+1;
16         b = rand()%100+1;
17 
18         if(num==1){
19             printf("%d + %d =\n",a,b);
20             printf("答案:%d\n\n",a+b);
21         }
22         else if(num==2){
23             printf("%d - %d =\n",a,b);
24             printf("答案:%d\n\n",a-b);
25         }
26         else if(num==3){
27             printf("%d × %d =\n",a,b);
28             printf("答案:%d\n\n",a*b);
29         }
30         else {
31             printf("%d ÷ %d =\n",a,b);
32             printf("答案:%f\n\n",a/b);
33         }
34     }
35 }