实验2

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;
    
    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++;
    }
    getchar();
    return 0;
}

代码srand(time(NULL));的作用：保证每次随机生成不同的学号

代码的目的：生成两个不同专业的五个随机学号

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;
}

total_price=0;如果去掉，会导致金额不被重置，下次购买时起始金额为本次购买金额

循环中continue语句作用：跳过本次循环中剩下的语句，进行下一次循环

task3

#include <stdio.h>

int main()
{
    char ch;
    
    while((ch=getchar())!=EOF){
        if(ch=='\n'){
            continue;
        }
        if(ch==103){
            printf("go go go\n");
        }
        else if(ch==121){
            printf("wait a minute\n");
            }
        else if(ch==114){
            printf("stop!\n");
            }
        else{
            printf("something must be wrong...\n");
           }
        while(getchar()!='\n');
    }
    return 0;
}

task4

#include<stdio.h>

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

task5

#include<stdio.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");
        }
        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 if(a==b&&b!=c||a==c&&c!=b||b==c&&c!=a){
            printf("等腰三角形\n");
        }
        else if(a==b,b==c){
            printf("等边三角形\n");
        }
        else{
            printf("普通三角形\n");
        }
    }
    return 0;
}

task6

#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main() {
    int random_num, i = 0, n = 0;

    srand(time(NULL));

    random_num = rand() % 30 + 1;
    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）:\n");


    for (n = 0; n < 3; n++) {
        scanf("%d", &i);
        if (i < random_num) {
            printf("你猜的日期早了，你的lucky day还没到呢\n");
            if (n < 2) {
                printf("再猜(1~30)：");
            }
        }
        else if (i > random_num) {
            printf("你猜的日期晚了，你的lucky day在前面哦\n");
            if (n < 2){
                printf("再猜(1~30)：");
            }
        }
        else {
            printf("哇，猜对了：)");
            break;
        }
        if (n == 2) {
            printf("次数用光啦。偷偷告诉你，11月你的lucky day是%d号\n", random_num);
        }
    }
    return 0;
}