实验2

实验任务1

源代码

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

 运行结果截图

问题1：生成5个在1到100之间的随机整数，并放在20490042后，按四位格式输出

问题2：生成1到100之间的随机数并赋值给number

问题3：固定按照四位输出，不足四位在前面补0

问题4：以系统时间作为随机数种子，让每次运行的随机数都不同

实验任务2

源代码

#include <stdio.h>
#include<stdlib.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");    
    system("pause");
    return 0;
}

 运行结果截图

问题1：如果去掉会使上一次的金额累加到下一次，导致计算出错

问题2：跳过本次循环的剩余代码，回到循环条件判断出开启下一轮循环

 实验任务3

源代码

#include<stdio.h>
#include<stdlib.h>
int main(){
    char color;
    printf("请输入信号灯颜色（r/g/y)\n");
    while(scanf("%c",&color)!=EOF){
        if(color=='\n'||color==' '){
            continue;
        }
        if(color=='r'){
            printf("stop!\n");
        }else if(color=='g'){
          printf("go go go\n");
        }else if(color=='y'){
          printf("wait a minute\n");
        }else{
          printf("something must be wrong...\n");
        }
        while(getchar()!='\n');
    }
    system("pause");
    return 0;
}

 运行结果截图

 实验任务4

源代码

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

int main() {
    double cost;
    double sum = 0.0;
    double max = 0.0;
    double min = 20000.0;
    int count = 0;

    printf("输入今日开销，直到输入-1终止：\n");

    while (1) {
        if (scanf("%lf", &cost) != 1) {
            break;
        }
        if (cost == -1) {
            break;
        }
        if (cost < 0 || cost > 20000) {
            continue;
        }
        if (count == 0) {
            max = cost;
            min = cost;
        }
        sum += cost;
        if (cost > max) {
            max = cost;
        }
        if (cost < min) {
            min = cost;
        }
        count++;
    }

    printf("今日累计消费总额：%.1f\n", sum);
    printf("今日最高一笔开销：%.1f\n", max);
    printf("今日最低一笔开销：%.1f\n", min);

    system("pause");
    return 0;
}

 运行结果截图

 实验任务5

源代码

#include<stdio.h>
#include<stdlib.h>
int main() {
    int a, b, c;
    while (scanf("%d%d%d", &a, &b, &c) != EOF) {
       
        if (a <= 0 || b <= 0 || c <= 0 ||
            (a + b <= c) || (a + c <= b) || (b + c <= a)) {
            printf("不能构成三角形\n");
            continue; 
        }
        if (a == b && b == 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");
        }
    }
    system("pause");
    return 0;
}

 运行结果截图

 实验任务6

 源代码

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

int main()
{
    int lucky_day;
    int guess;
    int n;

    srand((unsigned)time(NULL));
    lucky_day = rand() % 30 + 1;
    n = 0;

    printf("猜猜2026年4月哪一天是你的lucky day\n");
    printf("开始喽，你有3次机会，猜吧(1-30)：");

    while(n < 3)
    {
        scanf("%d", &guess);
        n++;

        if(guess == lucky_day)
        {
            printf("哇，猜中了:)\n");
            system("pause");
            return 0;
        }
        else if(guess > lucky_day)
            printf("你猜的日期晚了，你的lucky day在前面喔\n");
        else
            printf("你猜的日期早了，你的lucky day还没到呢\n");

        if(n < 3)
            printf("再猜(1-30)：");
    }

    printf("次数用光啦，4月你的lucky day是%d号\n", lucky_day);
    system("pause");
    return 0;
}

运行结果截图