作业二

实验一

#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)); // 以当前系统时间作为随机种子
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;
}

1.srand起到随机作用，去掉后运行结果均相同

2.功能为在两个班随机抽取5个学号

实验二

#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_s("%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_s("%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_s("%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;
}

1.去掉后影响下一次运行结果，使数据不断相加

2.continue使while循环重新运行

实验三

#include<stdio.h>
int main() {
    char x;
    while (1) {
        scanf_s("%c",&x);
        getchar();
        if(x=='r') {
            printf("stop!\n");
        }
        else if (x=='g') {
            printf("go go go\n");
        }
        else if (x == 'y') {
            printf("wait a minute\n");
        }
        else {
            printf("somthing must be wrong...\n");
        }
    }
    return 0;
}

实验四

#include<stdio.h>
int main() {
    float x=0,max,min,tt=0;
    printf("输入直至-1\n");
    scanf_s("%f", &x);
    min = x;
    max = x;
        while (x!=-1) {
            tt = x + tt;
            if (min >= x) {
                min = x;
            }
            else if(max<=x){
                max = x;
            }
            scanf_s("%f", &x);
        }
    printf("累计%.1f\n",tt);
    printf("最高%.1f\n",max);
    printf("最低%.1f\n",min);
    return 0;
}

实验五

#include<stdio.h>
int main() {
    int a, b, c;
    while (1) {
        scanf_s("%d%d%d", &a, &b, &c);
        if (a + b > c && b + c > a && a + c > b) {
            if (a * a == b * b + c * c || b * b == a * a + c * c || c * c == a * a + b * b) {
                printf("直角三角形\n");
            }
            else if (a == b&&b== c) {
                printf("等边三角形\n");
            }
            else if (a == b || b == c || c == a) {
                printf("等腰三角形\n");
            }
            else {
                printf("普通三角形\n");
            }
        }
        else
            printf("不是三角形\n");
    }
    return 0;
}

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define N 30
int main() {
    int a,b,c=0;
    srand(time(NULL));
    printf("猜猜11月哪一天是你的幸运日\n");
    b = rand() % N + 1;
    for (int i = 0; i < 3; i++) {
        scanf_s("%d",&a);
        getchar();
        if (a > b) {
            printf("大啦\n");
        }
        else if (a < b) {
            printf("小啦\n");
        }
        else if (a == b) {
            printf("猜对啦\n");
            c = 1;
        }
    }
    if (c==0) {
        printf("没机会啦\n");
    }
    return 0;
}