自动生成四则运算题目

#include"stdio.h"
main(){
    int  a,b,c,d;
    printf("自动生成四则运算：\n");
    printf("%d+%d= \n",a,b);    
    printf("%d-%d= \n",a,b);
    printf("%d*%d= \n",a,b);
    printf("%d/%d= \n",a,b);
} 

#include"stdio.h"
#include"stdlib.h"
#include"time.h"
main(){
    char i;
    int a,b,c,d,n,m,j,k,e;
    printf("**********自动生成四则运算***********\n");
    printf("1.开始\n");
    printf("2.退出\n");
    printf("请选择：\n");
    scanf("%d",&n);
    if(n==1){
    srand((unsigned)time(NULL));
        printf("请输入生成的题数：");
        scanf("%d",&m);
        for(j=0;j<m;j++){
            e=rand()%4;
            if(e==0){i=‘+‘;}
            if(e==1){i=‘-‘;}
            if(e==2){i=‘*‘;}
            if(e==3){i=‘/‘;}
            a=rand()%100;
            b=rand()%100;
            c=rand()%100;
            d=rand()%100;
            k=rand()%2;
            switch(k){
                case 0:printf("%d%c%d=\n",a,i,b);break;
                case 1:{if(a<=b&&c<=d)printf("%d/%d%c%d/%d=\n",a,b,i,c,d);
                        else if(a>b&&c>d) printf("%d/%d%c%d/%d=\n",b,a,i,d,c);
                        else if(a<=b&&c>d) printf("%d/%d%c%d/%d=\n",a,b,i,d,c);
                        else if(a>b&&c<=d) printf("%d/%d%c%d/%d=\n",b,a,i,c,d);
                        }break;
                }
                
            }
        
        }
     if(n==2){
        exit(0);
        return 0;
    }
}