实验二

#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++;
    }
    return 0;
 }

task1

有此行代码，多次运行结果不同

无此行代码，多次运行结果相同

作用是在不同运行时间随机生成不同种子，随机生成学号

#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;
 }

要求代码去掉则第一次计算准确，后续继续运行答案错误

跳过当前循环，直接进入下一次循环

任务2

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

任务三

#include<stdio.h>
int main(){
    float expense,total=0,max=0,min=20000;
    printf("输入今日开销，直到输入-1终止：\n");
    while(1){
        scanf("%f",&expense);
        if(expense==-1) break;
        total+=expense;
        if(expense>max)max=expense;
        if(expense<min)min=expense;
    }
    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;
}

任务四

#include<stdio.h>
int main(){
    int a,b,c;
    while(1){
        printf("请输入三角形三边边长（整数）：");
        if (scanf("%d%d%d",&a,&b,&c)!=3){
        break;
        }
        if (a>b){int t=a;a=b;b=t;}
        if (a>c){int t=a;a=c;c=t;}
        if (b>c){int t=b;b=c;c=t;}
        if(a+b<=c){
            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||b==c||a==c){
            printf("等腰三角形\n");
            }else if(a*a+b*b==c*c){
                printf("直角三角形");
            }else{
                printf("普通三角形\n");
                
            }
        
        
    }
    
}
return 0;
}

任务五

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main(){
    int lucky_day,guess,count=0;
    srand(time(0));
    lucky_day=rand()%30+1;
    printf("踩踩2025年11月的哪一天是你的lucky day\n");
    while(count<3){
        printf("开始喽，你有三次机会，猜吧（1-30）:");
        scanf("%d",&guess);
        count++;
        if(guess==lucky_day){
            printf("猜中啦：\n");
            break;
        
        }else if(guess>lucky_day){
            printf("你的日期猜晚了，你的lucky 打印在前面哦\n");
            
        }else if(guess<lucky_day){
            printf("你猜的日期早了，你的lucky day还没到呢\n");
            
        }
        if(count<3){
            printf("再猜(1-30):\n");
            
        }
    }
    if(count==3&&guess!=lucky_day){
        printf("次数用光了。偷偷告诉你，11月你的lucky day是%d号\n",lucky_day);
        
    }
    return 0;
}

任务六