#include <stdio.h>
#include<stdlib.h>
#include<time.h> 
int menu();
int help();
int error();
int operation_1();int one_1();
int operation_2();int two_1();
int operation_3();int three_1();
int main()
{
    int i;
    printf("========== 口算生成器 ==========\n");
    printf("欢迎使用口算生成器 ：\n");
    help();
    menu();
    while(1)
    {
        menu();
        scanf("%d",&i);
        switch(i)
        {
            case 1:operation_1();break;
            case 2:operation_2();break;
            case 3:operation_3();break;
            case 4:help();break;
        }
        printf("\n");
        if(i==5) break;
        if(i>5||i<1) error();
    }
    return 0;
}
help()
{
    printf("帮助信息\n");
    printf("您需要输入命令代号来进行操作\n");
    printf("一年级题目为不超过十位的加减法\n");
    printf("二年级题目为不超过百位的乘除法\n");
    printf("三年级题目为不超过百位的加减乘除混合题目\n");
    printf("\n");
}
menu()
{
    printf("操作列表:\n1)一年级    2)二年级    3)三年级\n");
    printf("4)帮助      5)退出程序\n请输入代号:");
}
error()
{
	printf("Error!!!\n");
    printf("错误操作指令，请重新输入\n\n");
} 
operation_1()
{
	printf("现在是一年级题目:\n");
    printf("请输入题目数量>");
    one_1();
}
operation_2()
{
	printf("现在是二年级题目:\n");
    printf("请输入题目数量>");
    two_1();
}
operation_3()
{
	printf("现在是三年级题目:\n");
    printf("请输入题目数量>");
    three_1();
}
one_1()
{
    int n,a,b,c;
    scanf("%d",&n);
    printf("一年级题目如下：\n"); 
    srand((unsigned)time(NULL));
    for(int i=1;i<=n;i++)
    {
        a=rand()%10+1;
        b=rand()%10+1;
        c=rand()%2;
        if(c==0)
        printf("%2d + %2d = ___",a,b);
        else
        printf("%2d - %2d = ___",a,b);
        printf("\n");
    } 
} 
two_1()
{
    int n,a,b,c;
    scanf("%d",&n);
    printf("二年级题目如下：\n"); 
    srand((unsigned)time(NULL));
    for(int i=1;i<=n;i++)
    {
        a=rand()%100;
        b=rand()%100;
        c=rand()%2;
        if(c==0)
        printf("%3d * %3d = ___",a,b);
        else
        printf("%3d / %3d = ___",a,b);
        printf("\n");
    } 
}
three_1()
{
    int n,a,b,c,d;
    scanf("%d",&n); 
    printf("三年级题目如下：\n"); 
    srand((unsigned)time(NULL));
    for(int i=1;i<=n;i++)
    {
        a=rand()%100;
        b=rand()%100;
        d=rand()%100;
        c=rand()%4;
        switch(c)
        {
            case 1:printf("%3d + %3d * %3d= ___",a,b,d);break;
            case 2:printf("%3d - %3d / %3d= ___",a,b,d);break;
            case 3:printf("%3d * %3d - %3d= ___",a,b,d);break;
            case 4:printf("%3d / %3d + %3d= ___",a,b,d);break;
        }
        printf("\n");
    }
}