实验2

1

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;

}
问题1：srand起到根据时间生成随机种子，保证每次程序运行时，初始种子不同，生成的随机数也不同，去掉的话，不会随机
问题2：生成5个随机数学号，运用随机种子
2

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;

}
问题1：每次循环中，total_price的存储不会释放，导致成一个累加的状态
问题2：直接跳出本次循环，进入下一次
3.

include<stdio.h>

int main() {
char deng;
while (scanf("%c",&deng)==1) {
if(deng == 'r') {
printf("stop!\n");
getchar();
}
else if (deng == 'g') {
printf("go go go\n");
getchar();
}
else if (deng == 'y') {
printf("wait a minute\n");
getchar();
}
else {
printf("something must be wrong\n");
getchar();
}
}
return 0;
}

4

include<stdlib.h>

include<stdio.h>

int main() {
printf("输入今天的开销，直到输入-1终止\n");
float money,max,min,sum =0;
scanf("%f",&money);
if (money ==-1)
exit(0);
else {
max=money;
min=money;
sum = money;
do {
scanf("%f",&money);
if (money!=-1) {
sum = sum +money;
if(money>max)
max=money;
if(money<min)
min=money;
}
}while (money!=-1);
printf("今日累计消费总额%.1f\n",sum);
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;
}
}

5

include<stdlib.h>

include<stdio.h>

include<math.h>

int main() {
int a,b,c;
while (scanf("%d%d%d",&a,&b,&c)3) {
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 {
int max=a>b?a:b;
max=max>c?max:c;
if ((pow(a,2)+pow(b,2)pow(max,2))||(pow(c,2)+pow(b,2)pow(max,2))||(pow(b,2)+pow(c,2)pow(max,2))) {
printf("直角三角形\n");
continue;
}
if (ab&&bc&&ca) {
printf("等边三角形\n");
continue;
}
if (ab||bc||ca) {
printf("等腰三角形\n");
continue;
}
printf("普通三角形\n");
}
}
return 0;
}

6

include<stdlib.h>

include<stdio.h>

include<math.h>

include<time.h>

int main() {
srand(time(NULL));
int lucky_day = rand()%30 +1;
int n = 3;
int guess;
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 (n--) {
scanf("%d",&guess);
printf("\n");
if (guess == lucky_day) {
printf("哇，猜中了：)\n");
break;
}
else if (guess< lucky_day) {
printf("你猜的日期早了，你的luck day还没到呢\n");
if (n!=0) {
printf("再猜(1~30)😊;
}
}
else {
printf("你猜的日期晚了，你的luck day在前面哦\n");
if (n!=0) {
printf("再猜(1~30)😊;
}
}
}
if (n==-1) {
printf("次数用光啦。偷偷告诉你，11月你的luck day是%d",lucky_day);
}
return 0;
}