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++;
  }
return 0;
}  

srand(time(NULL))的作用是根据系统时间取伪随机数

程序功能为从两个班里随机抽取五个学号，随机数为奇数则取20256343，后两位在0-79取余+1，中间两位补00；随机数为偶数则取20256136，后两位在0-34取余+1，中间两位补00。

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;
}

 删去total-price则下次运行会加上上次运行的total-price值

continue语义为跳出当次循环，继续下一次循环

 

task3

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

    }
    return 0;
}

 

task4

#include <stdio.h>
int main() {
    double a,max,min,total;
    int count;
    count = 0;
    a = 0;
    total = 0;
    printf("输入今日开销，直到输入-1终止:\n");
    
    
    while(1){
        scanf("%lf",&a);
        
        if(a>0&&a<=20000){
            if(count == 0){
                max = a;
                min = a;
            }
            else{
                if(max<=a){
                    max = a;   
                }   
                else if(min>=a){
                    min = a;
                }
                
            }
            total += a;
            count++;
        }
        else if(a==-1){
            printf("今日累计消费总额:%.1lf\n",total);
            printf("今日最高一笔开销:%.1lf\n",max);
            printf("今日最低一笔开销:%.1lf\n",min);
            break;
        }
        else{
            printf("输入数据有误，请重新输入:\n");
            continue;
        }
    }
    return 0;
}

 

task5

 

#include <stdio.h>
int main() {
    int a,b,c;
    int result;
    
    while((result = 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||a==c){
                if(a==b&&a==c&&b==c){
                    printf("等边三角形");
                }
                else{
                    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;
}

 

task6

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main() {
    srand(time(NULL));
    // 公式：[min, max] = rand() % (max - min + 1) + min
    int lucky_day =rand()%(30-1+1)+1;
    int gus,i;
    i = 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:");
    while(i<3){
        i++;
        scanf("%d",&gus);
        if(gus==lucky_day){
            printf("哇，猜中了:)\n");
            break;
        }
        else if(gus<lucky_day){
            printf("你猜的日期早了，你的lucky day还没到呢\n");        
        }
        else if(gus>lucky_day){
            printf("你猜的日期晚了，你的lucky day在前面哦\n");        
        }
        if(i==3){
            printf("次数用光啦。偷偷告诉你，11月的lucky day是%d号",lucky_day);    
        }
        else{
            printf("再猜(1~30):");    
        }
    }
    return 0;
}