实验2

 

task1

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);
    }
    return 0;
}

运行结果截图

 

回答问题

问题一：随机生成五个204900420001-204900420100之间的学号

问题二：生成一个1-100的随机数

问题三：保证20490042后面是四位数

问题四：使每次rand（）生成的随机数不同

task2

源代码

#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;
}

运行结果截图

回答问题

问题一：去掉line47会导致购买时会把上一次的总价加到新的总价上

问题二：跳过continue之后语句，直接进入下一次循环条件判断

task3

源代码

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

运行结果截图

task4

源代码

#include <stdio.h>

int main() {
    double expense;
    double total = 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) {
        scanf("%lf", &expense);
        if (expense == -1) {
            break;
        }
        if (expense <= 0 || expense > 20000) {
            continue;
        }
        if (expense > max) max = expense;
        if (expense < min) min = expense;
        total += expense;
        count++;
    }
        printf("今日累计消费总额：%.1f\n", total);
        printf("今日最高一笔开销：%.1f\n", max);
        printf("今日最低一笔开销：%.1f\n", min);

    return 0;
}

运行结果截图

task5

源代码

#include <stdio.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){
        printf("不能构成三角形\n");}
        else{
         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");
        }
        }        
    }
    return 0;
}

运行结果截图

 task6

源代码

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

int main() {
    int lucky_day, guess;
    int chances = 3;
    srand(time(0));
    lucky_day = rand() % 30 + 1;
    printf("猜测2026年4月哪天是你的lucky day\n");
    printf("开始喽，你有3次机会，猜吧(1~30)：");
    while (chances > 0) {
        scanf("%d", &guess); 
        if (guess == lucky_day) {
            printf("哇，猜中了\n");
            break;
        } else if (guess < lucky_day) {
            printf("你猜的日期早了，你的lucky day还没到呢\n");
        } else {
            printf("你猜的日期晚了，你的lucky day在前面哦\n");
        }
        chances--;
        if (chances > 0) {
            printf("再猜(1~30)：");
        } else {
            printf("次数用光啦。4月你的lucky day是%d号\n", lucky_day);
        }
    }
    
    return 0;
}

运行结果截图