实验2

一

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define N 5

int main()
{
    int number;
    int i;

    srand(time(0));
    for (i = 0; i < N;++i)
    {
        number = rand() % 100 + 1;
        printf("20490042%04d\n", number);
    }
    return 0;
}

1、随机一个【1,101】之间的数；2、；3、根据不同的时间随机一个整数。

二

#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_s("%d", &choice);

        if (choice == 0)
            break;
        if (choice < 1 or 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_s("%d", &quantity);

        if (quantity < 0)
        {
            printf("购买数量不能为负数，请重新输入。\n");
            continue;
        }
        switch (choice)
        {
        case 1:
        case 2:
            total_price += 3 * quantity;
            break;
        case 3:
            total_price += 5 * quantity;
            break;
        case 4:
            total_price += 2 * quantity;
            break;
        }
        printf("请投入金额：");
        scanf_s("%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("感想您的购买，欢迎下次光临!\n");
    return 0;
}

1、清空前面输入的数据，删去数据初始值会改变；2、break指不继续往下重新开始一轮循环，continue指继续往下进行；3、不用，因为程序逻辑完善再加入default语句反而啰嗦。

三

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
    char color;

    while (scanf(" %c", &color)!=EOF)
    {
        switch (color)
        {
        case 'r':
            printf("stop!\n");
            break;
        case 'g':
            printf("go go go\n");
            break;
        case 'y':
            printf("wait a minute\n");
            break;
        default:
            printf("something must be wrong...\n");
            break;
        }
        
    }
    return 0;
}

 

四

#include <stdio.h>
int main()
{
    int n,x,max,min;
    int sum;
    printf("输入今日开销，直到输入-1终止：\n");
    scanf_s("%d", &x);
    max = x;
    min = x;
    sum = x;
    n = 0;
    while (1){
        scanf_s("%d", &n);
        if (n == -1)
            break;
        if (n > max)
            max = n;
        if (n < min)
            min = n;
        sum += n;
    }
    
    printf("今日累计消费总额：%d\n",sum);
    printf("今日最高一笔开销：%d\n",max);
    printf("今日最低一笔开销：%d\n",min);
    return 0;
}

 

五

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{
    int i,n;
    
    srand(time(NULL));
    int random_number = 1 + rand()%30;
    int x = random_number;

    printf("猜猜2025年4月哪一天是你的lucky day\n");
    printf("开始喽，你有三次机会，猜吧（1-30）：");
    scanf_s("%d", &n);
    for (i = 0; i < 3; ++i)
    {

        if (n < x)
        {
            printf("你猜的日期早了，你的lucky day还没到呢\n");
            
        }
        else if (n > x)
        {
            printf("你猜的日期晚了，你的lucky day在前面哦\n");
            
        }
        else
        {
            printf("哇，猜中了:-)\n");
            break;
        }
        if (i < 2) {
            printf("再猜（1-30）：");
            scanf_s("%d", &n);
        }
        else
            printf("次数用完啦，偷偷告诉你你的lucky day是%d号", x);
    }
    
    return 0;
}

 

六

#include<stdio.h>

int main()
{

    int n, i, j;
    printf("input n: ");
    scanf_s("%d", &n);

    for (i = n; i > 0; i--)
    {
        for (j = 0; j < n - i; j++)
            printf(" \t");

        for (j = 0; j < 2 * i - 1; j++)
            printf(" O \t");

        printf("\n");

        for (j = 0; j < n - i; j++)
            printf(" \t");

        for (j = 0; j < 2 * i - 1; j++)
            printf("<H>\t");

        printf("\n");

        for (j = 0; j < n - i; j++)
            printf(" \t");

        for (j = 0; j < 2 * i - 1; j++)
            printf("I I\t");

        printf("\n");
        printf("\n");
    }

    return 0;
}