Practice1小学四则运算（改进）

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
void srand(unsigned);//随机生成不同的数
void main()
{
    int n,i,a,b,c,d,e,f,g,h,j;
    printf("****************************欢迎使用！************************\n");
    printf("\n");
    printf("1.加法运算\n");
    printf("2.减法运算\n");
    printf("3.乘法运算\n");
    printf("4.除法运算\n");
    printf("0.退出程序\n");
    printf("***************************************************************\n");
    printf("请选择运算类型:");
    scanf("%d", &n);
    while(n<||n>)
    {
        printf("输入错误,请重新输入:\n");
        scanf("%d",&n);
    }
    switch(n)
    {
    case :
        {
            printf("***************************************************************\n");
            printf("5.一位数加一位数\n");
            printf("6.一位数加两位数\n");
            printf("7.两位数加两位数\n");
            printf("***************************************************************\n");
            printf("请输入题型:");
            scanf("%d",&i);
            while(i<||i>)
            {
                printf("输入错误,请重新输入:\n");
                scanf("%d",&i);
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                a=rand()%+;
                b=rand()%+;
                c=a+b;
                printf("%d+%d=\n",a,b);
                printf("请输入答案:\n");
                scanf("%d",&d);
                while(d!=c)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d+%d=\n",a,b);
                    scanf("%d",&d);
                }
                printf("回答正确!\n");
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                a=rand()%+;
                b=rand()%+;
                c=a+b;
                printf("%d+%d=\n",a,b);
                printf("请输入答案:\n");
                scanf("%d",&d);
                while(d!=c)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d+%d=\n",a,b);
                    scanf("%d",&d);
                }
                printf("回答正确!\n");

            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                a=rand()%+;
                b=rand()%+;
                c=a+b;
                printf("%d+%d=\n",a,b);
                printf("请输入答案:\n");
                scanf("%d",&d);
                while(d!=c)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d+%d=\n",a,b);
                    scanf("%d",&d);
                }
                printf("回答正确!\n");
            }

            break;
        }

    case :
        {
            printf("***************************************************************\n");
            printf("5.一位数减一位数\n");
            printf("6.两位数减一位数\n");
            printf("7.两位数减两位数\n");
            printf("***************************************************************\n");
            printf("请输入题型:");
            scanf("%d",&i);
            while(i<||i>)
            {
                printf("输入错误,请重新输入:\n");
                scanf("%d",&i);
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                c=rand()%+;
                d=rand()%+;
                e=c-d;
                printf("%d-%d=\n",c,d);
                printf("请输入答案:\n");
                scanf("%d",&g);
                while(g!=e)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d-%d=\n",c,d);
                    scanf("%d",&g);
                }
                printf("回答正确!\n");
            }

            if(i==)
            {
                srand((unsigned)time(NULL));
                c=rand()%+;
                d=rand()%+;

                e=c-d;
                printf("%d-%d=\n",c,d);
                printf("请输入答案:\n");
                scanf("%d",&g);
                while(g!=e)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d-%d=\n",c,d);
                    scanf("%d",&g);
                }
                printf("回答正确!\n");
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                c=rand()%+;
                d=rand()%+;
                e=c-d;
                printf("%d-%d=\n",c,d);
                printf("请输入答案:\n");
                scanf("%d",&g);
                while(g!=e)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d-%d=\n",c,d);
                    scanf("%d",&g);
                }
                printf("回答正确!\n");
            }
            break;
        }

    case :
        {
            printf("***************************************************************\n");
            printf("5.一位数乘一位数\n");
            printf("6.一位数乘两位数\n");
            printf("7.两位数乘两位数\n");
            printf("***************************************************************\n");
            printf("请输入题型:");
            scanf("%d",&i);
            while(i<||i>)
            {
                printf("输入错误,请重新输入:\n");
                scanf("%d",&i);
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                e=rand()%+;
                f=rand()%+;
                g=e*f;
                printf("%d*%d=\n",e,f);
                printf("请输入答案:\n");
                scanf("%d",&h);
                while(h!=g)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d*%d=\n",e,f);
                    scanf("%d",&h);
                }
                printf("回答正确!\n");
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                e=rand()%+;
                f=rand()%+;

                g=e*f;
                printf("%d*%d=\n",e,f);
                printf("请输入答案:\n");
                scanf("%d",&h);
                while(h!=g)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d*%d=\n",e,f);
                    scanf("%d",&h);
                }
                printf("回答正确!\n");
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                e=rand()%+;
                f=rand()%+;

                g=e*f;
                printf("%d*%d=\n",e,f);
                printf("请输入答案:\n");
                scanf("%d",&h);
                while(h!=g)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d*%d=\n",e,f);
                    scanf("%d",&h);
                }
                printf("回答正确!\n");
            }
            break;
        }
    case :
        {
            printf("***************************************************************\n");
            printf("5.一位数除于一位数\n");
            printf("6.两位数除于一位数\n");
            printf("7.两位数除于两位数\n");
            printf("***************************************************************\n");
            printf("请输入题型:");
            scanf("%d",&i);
            while(i<||i>)
            {
                printf("输入错误,请重新输入:\n");
                scanf("%d",&i);
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                g=rand()%+;
                h=rand()%+;
                i=g/h;
                printf("%d/%d=\n",g,h);

                printf("请输入答案:\n");
                scanf("%d",&j);
                while(j!=i)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d/%d=\n",g,h);
                    scanf("%d",&j);
                }
                printf("回答正确!\n");

            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                g=rand()%+;
                h=rand()%+;

                i=g/h;
                printf("%d/%d=\n",g,h);

                printf("请输入答案:\n");
                scanf("%d",&j);
                while(j!=i)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d/%d=\n",g,h);
                    scanf("%d",&j);
                }
                printf("回答正确!\n");
            }
            if(i==)
            {
                srand((unsigned)time(NULL));
                g=rand()%+;
                h=rand()%+;

                i=g/h;
                printf("%d/%d=\n",g,h);

                printf("请输入答案:\n");
                scanf("%d",&j);
                while(j!=i)
                {
                    printf("回答错误，请重做:\n");
                    printf("%d/%d=\n",g,h);
                    scanf("%d",&j);
                }
                printf("回答正确!\n");

            }
            break;
        }
    case :
        {
            printf("谢谢使用！再见！\n");
            break;
        }
 }

}

这次每次生成的题目都不同，也可以进行判断正误，但感觉代码过多重复冗杂0.0，不知如何缩进又不改变原本的功能0.0。