实验2

实验任务1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5
#define N1 80
#define N2 35
int main() {
    int cnt;
    int random_major, random_no;
    srand(time(NULL));      // 以当前系统时间作为随机种子
    cnt = 0;
    while(cnt < N) {
        random_major = rand() % 2;
        if(random_major) {
            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;
}

1.获得一个基于时间的随机值

2.基于时间生成学生的随机学号

实验任务2

#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;
}

 1.上次购买时已赋值的total_price会影响到下一次的输入

2.符合条件时，继续进行下一次循环

实验任务3

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int main() {
char ch;
while(scanf(" %c",&ch)!=EOF){
if(ch=='r')
printf("stop!\n");
else if(ch=='g')
printf("go go go\n");
else if(ch=='y')
printf("wait a minute\n");
else
printf("something must be wrong...\n");
}

return 0;
}

 实验任务4

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int main() {
    double cost;
    double total = 0.0;
    double max = 0.0;
    double min = 20000.0;
    printf("输入今日开销，直到输入-1终止:\n");
    while (1) {
        scanf("%lf", &cost);
        if (cost == -1) {
            break;
        }
        total += cost;
        if (cost > max) {
            max = cost;
        }
        if (cost < min) {
            min = cost;
        }

    }
    printf("进入累计消费总额: %.1lf\n", total);
    printf("今日最高一笔开销: %.1lf\n", max);
    printf("今日最低一笔开销: %.1lf\n", min);

    return 0;
}

 实验任务5

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int main() {
int a, b, c;
while (scanf("%d %d %d", &a, &b, &c) != EOF)
{
if (a + b > c && a + c > b && b + c > a) {
if (a == b && a == c) {
printf("等边三角形\n");
}
else if (a == b || a == c || b == c) {
printf("等腰三角形\n");
}
else if (a * a + b * b == c * c || a * a + c * c == b * b || b * b + c * c == a * a)
{
printf("直角三角形\n");
}
else {
printf("普通三角形\n");
}
}
else
printf("不能构成三角形\n");
}
return 0;
}

 实验任务6

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include<time.h>
int main() {
    int day, guess;
    srand(time(NULL));
    day = rand() % 30 + 1;
    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)：");
    for (int i = 0; i < 3; i++) {
        scanf("%d", &guess);
        if (guess == day) {
            printf("哇，猜中了：)\n");
            break;
        }
        else if (guess < day) {
            printf("你猜的日期早了，你的lucky day还没到呢\n");
            printf("再猜（1~30）：");
        }
        else {
            printf("你猜的日期晚了，你的lucky day在前面哦\n");
            printf("再猜（1~30）：");
        }
        if (i == 2) {
            printf("次数用光啦。偷偷告诉你，11月你的lucky day是%d号\n", day);
        }
    }

    return 0;
}