task2

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));
    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++;
    }
    system("pause");
    return 0;
}

 

 

多次运行代码，生成的数据不同

该代码的作用是获取随时在变的随机数

该程序的作用是随机获取几组学号数据

 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);
    }
    printf("感谢您的购买，欢迎下次光临！\n");
    total_price = 0;
    return 0;
}

问题1：去掉后，下一次循环时总价格不为零，初始值会是上一次的价格

问题2：continue的语义是中止执行后面的代码并重新开始新循环

任务3

#include <stdio.h>
int main() {
    char a;
    while (1) {
        scanf("%c", &a);
        if (a == 'r')
            printf("stop!\n");
        else if (a == 'y')
            printf("wait a minute\n");
        else if (a == 'g')
            printf("go go go\n");
        else
            printf("something must be wrong...\n");
        scanf("%c",&a);
    }
    return 0;
    }

任务4

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main() {
    printf("输入今日开销，直到输入-1中止\n");
    double max, min,total, a;
    max = 0;
    min = 20000;
    total = 0;
    char b;
    while (1) {
        scanf("%lf", &a);
        if (a != -1)
        {
            if (a > max)
                max = a;
            if (a < min)
                min = a;
            total += a;
        }
        else
            break;
    }
    printf("今日累计消费总额：%.01lf\n", total);
    printf("今日最高一笔开销：%.01lf\n", max);
    printf("今日最低一笔开销：%.01lf\n", min);
    return 0;
    }

任务5

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

    }
    return 0;
    }

 任务6

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main() {
    int a, b,c;
    srand(time(NULL));
    a = rand()%30+1;
    printf("猜猜2025年11月哪一天是你的lucky day\n");
    printf("你有3次机会，猜吧：");
    for (c = 1; c <= 3; c++)
    {
        scanf("%d",&b);
        if (a == b) {
            printf("哇，猜中了:)");
            return 0;
        }
        if (a <= b)
            printf("你猜的时间晚了，你的lucky day在前面哦\n");
        else
            printf("你猜的时间早了，你的lucky day还没到呢\n");
        if (c<3)
            printf("再猜：");
    }
    printf("次数用光了，偷偷告诉你，11月你的lucky day是：%d", a);
    return 0;
}