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("20256343504D\n",random_no);
        }
        else{
            random_no = rand() % N2 + 1;
            printf("20256136%04d\n",random_no);
        }

        cnt++;
    }
    system("pause");
    return 0;
}

 

 srand(time(NULL))作用是使每次运行生成不同随机数序列

任务二

#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;
}

去掉后每次购买后价格不会清零而是一直累加；语义是跳过循环中剩余指令进行下一指令

#include <stdio.h>
int main() {
    char color;
    while ((color = getchar()) != -1) {
        if (color == '\n') {
            continue;
        }
        if (color == 'r') {
            printf("stop!\n");
        }
        else if (color == 'g') {
            printf("go go go\n");
        }
        else if (color == 'y') {
            printf("wait a minute\n");
        }
        else {
            printf("something must be wrong...\n");
        }
        while (getchar() != '\n');
    }
    return 0;
}

#include <stdio.h>
int main() {
    double expense, total = 0.0;
    double maxExpense = 0.0, minExpense = 20000.0;
    printf("输入今日开销，直到输入-1终止：\n");
    while (1) {
        scanf_s("%lf", &expense);
        if (expense == -1) {
            break;
        }
        if (expense > maxExpense) {
            maxExpense = expense;
        }
        if (expense < minExpense) {
            minExpense = expense;
        }
        total += expense;
    }
    printf("今日累计消费总额：%.1f\n", total);
    printf("今日最高一笔开销：%.1f\n", maxExpense);
    printf("今日最低一笔开销：%.1f\n", minExpense);
    return 0;
}

#include <stdio.h>
int main() {
    int a, b, c;
    while (scanf_s("%d %d %d", &a, &b, &c) != -1) {
        if (a + b > c && a + c > b && b + c > a) {
            if (a == b && b == c) {
                printf("等边三角形\n");
            }
            else if (a == b || a == c || b == c) {
                if ((a * a + b * b == c * c) || (a * a + c * c == b * b) || (b * b + c * c == a * a)) {
                    printf("等腰直角三角形\n");
                }
                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");
            }
        }
        else {
            printf("不能构成三角形\n");
        }
    }
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main() {
    srand((unsigned int)time(NULL));
    int luckyDay = rand() % 30 + 1;
    int guess, count = 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(1~30)：");
    while (count < 3) {
     scanf_s("%d", &guess);
        count++;
        if (guess == luckyDay) {
            printf("哇，猜中了:)\n");
            return 0;
        }
        else if (guess < luckyDay) {
            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");
        }
        if (count < 3) {
            printf("再猜(1~30)：");
            scanf_s("%d", &guess);
            count++;
            if (guess == luckyDay) {
                printf("哇，猜中了:)\n");
                return 0;
            }
            else if (guess < luckyDay) {
                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");
            }
        }
    }
    printf("次数用光啦。偷偷告诉你，11月你的lucky day是%d号\n", luckyDay);
    return 0;
}