实验2

task1.c源代码
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#include<stdlib.h>
#include<time.h>

#define N 5
#define N1 80
#define N2 35

int main(){
	int cnt;
	int random_majior, random_no;
    srand(time(NULL));
	

	cnt = 0;
	while (cnt < N) {
		random_majior = rand() % 2;

		if (random_majior) {
			random_no = rand() % N1 + 1;
			printf("20256343%04d\n", random_no);

		}
		else {
			random_no = rand() % N2 + 1;
			printf("20256136%04d\n", random_no);

		}
		cnt++;

	}
	return 0;
}

运行结果截图

去掉前：

两次随机生成的数字不同

去掉后：

两次随机生成的数虽然随机但相同

回答问题

srand(time(NULL))的作用：设置随机数种子，使生成的数字完全随机

程序的作用：随机生成两个专业的学号中的5个学号

task2.c源代码
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#include <stdio.h>
int main() {
    int choice, quantity;
    float total_price = 0, amount_paid, change;
    while (1) {
        printf("\n自动饮料售卖机菜单:\n");
        printf("1. 可乐 - 3 元/瓶\n");
        printf("2. 雪碧 - 3 元/瓶\n");
        printf("3. 橙汁 - 5 元/瓶\n");
        printf("4. 矿泉水 - 2 元/瓶\n");
        printf("0. 退出购买流程\n");
        printf("请输入饮料编号: ");
        scanf("%d", &choice);
        if (choice == 0)
            break;
        if (choice < 1 || choice > 4) {
            printf("无效的饮料编号，请重新输入。\n");
            continue;
        }
        printf("请输入购买的数量: ");
        scanf("%d", &quantity);
        if (quantity < 0) {
            printf("购买数量不能为负数，请重新输入。\n");
            continue;
        }
        if(choice == 1 || choice == 2)
            total_price += 3 * quantity;
        else if(choice == 3)
            total_price += 5 * quantity;
        else
            total_price += 2 * quantity;
        printf("请投入金额: ");
        scanf("%f", &amount_paid);
        change = amount_paid - total_price;
        printf("本次购买总价: %.2f 元\n", total_price);
        printf("找零: %.2f 元\n", change);
        total_price = 0;
    }
    printf("感谢您的购买，欢迎下次光临！\n");
return 0;
}

运行结果截图

回答问题

若去掉line 47,会引发程序异常导致中止

continue的作用：继续循环中的下一步

task3.c源代码
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#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>

int main() {
	char color;


	while (1) {
		scanf("%c", &color);
		getchar();
		if (color == 'y')
		{
			printf("wait a minute\n");
		}
		else if (color == 'r')
		{
			printf("stop!\n");
		}
		else if (color == 'g')
		{
			printf("go go go\n");
		}
		else
		{
			printf("something must be wrong...\n");
		}
	}
	return 0;
}

运行结果截图

task4.c源代码
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#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>

int main() {

	double sum = 0, max_num = 0, min_num = 20000, num;


	printf("输入今日开销，直到输入-1时终止：\n");
	while (1) {
		scanf("%lf", &num);
		if (num > max_num) {
			max_num = num;
		}
		if (num > 0 && num < min_num) {
			min_num = num;
		}
		sum += num;
		if (num == -1)
			break;
	}
	printf("今日累计消费总额：%.1lf\n", sum);
	printf("今日最高一笔开销：%.1lf\n", max_num);
	printf("今日最低一笔开销：%.1lf\n", min_num);
	return 0;
}

运行结果截图

task5.c源代码
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#include<stdio.h>

int main() {

	int a, b, c;

	while (1) {
		scanf("%d %d %d", &a, &b, &c);
		if(a + b <= c || a + c <= b || c + b <= a) {
			printf("不能构成三角形\n"); 
		}
		else {

			if ((a * a) + (b * b) == (c * c) || (c * c) + (b * b) == (a * a) || (a * a) + (c * c) == (a * a)) {
				printf("直角三角形\n");
			}
			else if (a == b&&c != b || a == c&&c != b || b == c&&a != b) {
				printf("等腰三角形\n");
			}
			else if (a == b && a == c) {
				printf("等边三角形\n");
			}
			else {
				printf("普通三角形\n");
			}
		}
	}
	return 0;
}

运行结果截图

task6.c源代码
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#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<time.h>

int main() {

	int num, i = 0;

	int min = 1, max = 30;
	srand((unsigned int)time(NULL));
	int luckyday = rand() % (max - min + 1) + min;

	printf("猜猜2025年11月哪一天是你的lucky day\n");
	printf("开始喽，你有三次机会，猜吧（1~30）：");
	
	while (i <3) {
		i++;
		scanf("%d", &num);
		if (num == luckyday) {
			printf("哇，猜中了:)\n");
			return 0;
		}
		else if (num < luckyday) {
			printf("你猜的日期早了，你的lucky day还没到呢\n");
		}
		else 
			printf("你猜的日期晚了，你的lucky day在前面哦\n");
			if (i < 3)
			{
				printf("再猜\n");
			}
		}
		printf("次数用光了。偷偷告诉你，11月你的lucky day是%d", luckyday);

	}

运行结果截图