实验二

Task1:

#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;
    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;
}

 

 

 

 

问题一：代码srand(time(NULL))可以生成随机数据种子

问题二：生成以20256343或20256136开头的五组学号

 

 

Task2：

#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;
}

 

问题一：删除后运行时购买总价会把上一次的金额算入

问题二：continue的作用是立即跳过当前循环的剩余代码，直接进入下一循环

Task3：

#include <stdio.h>
int main() 
{
    char colour;
    printf("红绿灯颜色\n");
    while (1)
    
    {
        colour = getchar ();
        if (colour == EOF)
        {
            break;
        }
        if (colour == '\n')
        {
            continue;  
        }
    
        if (colour == 'r')
        {
            printf("stop!\n");

        }
        else if (colour == 'g')
        {
            printf("go go go\n");
        }
        else if (colour == 'y')
        {
            printf("wait a minute\n");
        }
        else 
        {
            printf("something must be wrong...\n");
        }

    }
    
    return 0;
}

 Task4:

#include <stdio.h>
int main() 
{
    double a,max,min = 20000,sum = 0;
    printf("输入今日开销，直到输入-1终止:\n");
    scanf("%lf\n",&a);

    while (a != -1)
    {
        sum += a;
        
        if (a > max)
        {
            max = a;
        } 
        if (a < min)
        {
            min = a;
        }
        if (a > 0 && a <= 20000)
        {
            scanf("%lf",&a);
        }
    }
             
    printf("今日累计消费总额:%.2lf\n",sum);
    printf("今日最高一笔开销:%.2lf\n",max);
    printf("今日最低一笔开销:%.2lf\n",min);
    
    
    return 0;
}

 

Task5:

 

#include <stdio.h>
int main() 
{
    int a,b,c;
    while(1) 
    {  
        printf("请输入三角形三边长度（整数）\n");
        scanf("%d%d%d",&a,&b,&c);
        if ( a + b > c && a + c > b && b + c > a )
        {
            if( a == b && b == c)
            printf("等边三角形\n");
            else if(a * a + b * b == c * c || b * b + c * c == a * a || a * a + c * c == b * b)
            printf("直角三角形\n");
            else if( a == b || c == b || a == c)
            printf("等腰三角形\n");
            else 
            printf("普通三角形\n");

        }
        else
        printf("不能构成三角形\n");
    }
    return 0;
}

 

Task6:

 

#include <stdio.h>
int main() 
{
    srand(time(NULL));
    int a = rand()%30 + 1;
    int x;
    int count = 0;
    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(count < 3)
    {
        count ++;
        scanf("%d",&x);
        if(x > a)
        printf("你猜的日期晚了,你的lucky day在前面嗷\n");
        else if(x < a)
        printf("你猜的日期早了,你的lucky day还没到呢\n");
        else 
        {
            printf("哇，猜中了");
            break;
        }
    }
    if (count >= 3)
    printf("次数用光了。偷偷告诉你,你的lucky day是%d号",a);
    return 0;
}