C语言寒假大作战04

1 作业头：

这个作业属于哪个课程	https://edu.cnblogs.com/campus/zswxy/CST2019-2
这个作业要求在哪里	https://edu.cnblogs.com/campus/zswxy/CST2019-2/homework/10279
这个作业的目标	使用函数、Switch语句来完成菜单程序
作业正文	https://i-beta.cnblogs.com/posts/edit
参考文献	https://www.runoob.com/cprogramming/c-function-rand.html https://zhidao.baidu.com/question/271899014.html

2 设计思路和遇到的问题

1.在三年级的题中一直想不到什么好方法，就把可能的情况全部printf了。
2.在除法中0/会出现不等于0的情况，所以加上(double)a/b。

3 程序结果截图

4 程序代码

#include<stdio.h>
#include<stdlib.h>
#include<time.h> 
void first(int opt) {
	int i,n,a,b;
	char op[] = { '+','-' };
	srand(time(NULL));
	printf("/*----- 一年级 -----*/\n");
	printf("<请输入生成个数> ");
	scanf_s("%d", &n);
	for (i = 1; i <= n; i++)
	{
		a = rand() % 10;
		b = rand() % 10;
		switch (op[rand() % 2])
		{
		case '+': printf("%d + %d = %d\n", a, b, a + b); break;
		case '-': printf("%d - %d = %d\n", a, b, a - b); break;
		}
	}
}
void second(int opt) {
	int i,n,a,b;
	char op[] = { '*','/' };
	srand(time(NULL));
	printf("/*----- 二年级 -----*/\n");
	printf("<请输入生成个数> ");
	scanf_s("%d", &n);
	for (i = 1; i <= n; i++)
	{
		a = rand() % 10;
		b = rand() % 9 + 1;
		switch (op[rand() % 2])
		{
		case '*': printf("%d * %d = %d\n", a, b, a * b); break;
		case '/': printf("%d / %d = %g\n", a, b, (double)a / b); break;
		}
	}
}
void third(int opt) {
	int i,n,a,b,c;
	char op[] = { '*','/','+','-' };
	srand(time(NULL));
	printf("/*----- 三年级 -----*/\n");
	printf("<请输入生成个数> ");
	scanf_s("%d", &n);
	for (i = 1; i <= n; i++)
	{
		a = rand() % 100;
		b = rand() % 9 + 1;
		c = rand() % 9 + 2;
		switch (rand() % 16 + 1)           //16种情况/
		{
		case 1: printf("%d + %d + %d = %d\n", a, b, c, a + b + c); break;
		case 2: printf("%d + %d - %d = %d\n", a, b, c, a + b - c); break;
		case 3: printf("%d + %d * %d = %d\n", a, b, c, a + b * c); break;
		case 4: printf("%d + %d / %d = %g\n", a, b, c, (double)a + b / c); break;
		case 5: printf("%d - %d + %d = %d\n", a, b, c, a - b + c); break;
		case 6: printf("%d - %d - %d = %d\n", a, b, c, a - b - c); break;
		case 7: printf("%d - %d * %d = %d\n", a, b, c, a - b * c); break;
		case 8: printf("%d - %d / %d = %g\n", a, b, c, (double)a - b / c); break;
		case 9: printf("%d * %d + %d = %d\n", a, b, c, a * b + c); break;
		case 10: printf("%d * %d - %d = %d\n", a, b, c, a * b - c); break;
		case 11: printf("%d * %d * %d = %d\n", a, b, c, a * b * c); break;
		case 12: printf("%d * %d / %d = %g\n", a, b, c, (double)a * b / c); break;
		case 13: printf("%d / %d + %d = %g\n", a, b, c, (double)a / b + c); break;
		case 14: printf("%d / %d - %d = %g\n", a, b, c, (double)a / b - c); break;
		case 15: printf("%d / %d * %d = %g\n", a, b, c, (double)a / b * c); break;
		case 16: printf("%d / %d / %d = %g\n", a, b, c, (double)a / b / c); break;
		}
	}
}
void help(int opt) {
	printf("帮助信息\n您需要输入命令代号来进行操作, 且\n");
	printf("一年级题目为不超过十位的加减法;\n二年级题目为不超过百位的乘除法;\n三年级题目为不超过百位的加减乘除混合题目.\n\n\n");
}
void end(int opt) {
	printf("程序结束, 欢迎下次使用,任意键结束......\n\n");
}
void error(int opt) {
	printf("Error!!!\n错误操作指令, 请重新输入\n\n\n");
}
int main()
{
	int opt = -1;
	printf("========== 口算生成器 ==========\n欢迎使用口算生成器 :\n\n");
	printf("帮助信息\n您需要输入命令代号来进行操作, 且\n");
	printf("一年级题目为不超过十位的加减法;\n二年级题目为不超过百位的乘除法;\n三年级题目为不超过百位的加减乘除混合题目.\n\n\n");
	while (opt != 5)
	{
		printf("操作列表:\n1)一年级    2)二年级    3)三年级\n4)帮助      5)退出程序\n ");
		printf("请输入操作 >\n\n");
		scanf_s("%d", &opt);
		switch (opt) {
		case 1:first(opt); break;
		case 2:second(opt); break;
		case 3:third(opt); break;
		case 4:help(opt); break;
		case 5:end(opt); break;
		default:error(opt); break;
		}
	}
}

5 Gitee上传截图与链接

6 主页地址

https://gitee.com/feng_yue_long