实验二

task1

代码：#include <stdio.h>#include <stdlib.h>#include <time.h>#define N 5int main() {   int number;   int i;   srand(time(0));     // 以当前系统时间作为随机种子   for(i = 0; i < N; ++i) {       number = rand() % 100 + 1;  printf("20490042%04d\n", number);  }   return 0;}

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q1：随机生成1~100之间的整数

q2：rand()是生成0~RAND之间的最大数，然后%100对100取余，最后加一让结果在1~100

q3：%d输出十进制整数，4表示四位，0表示左侧不足四位，用0不齐

q4：刷新随机数，如果去掉这个，每次运行结果都是一样的

task2

代码：

#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;}

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q1：其用于刷新重置，如果删去，会在下一次付款加上上一次的总价，产生错误

q2：跳过剩余循环，重新回到开始，开始新的循环

task3

代码：#include<stdio.h>int main(){char color;printf("输入颜色(g/r/y):\n");while(scanf("%c",&color)==1){getchar();if(color=='g')printf("go go go\n");else if(color=='r')printf("stop!\n");else if(color=='y')printf("wait a minute\n");else printf("sth must be wrong...\n");}return 0;}

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task4

代码：#include <stdio.h>int main() {double x, sum = 0, max = 0, min = 20000;printf("输入今日开销，直到输入-1终止：\n");while (1) {scanf("%lf", &x);if (x == -1) break;if (x <= 0 || x > 20000) continue;sum += x;if (x > max) max = x;if (x < min) min = x;}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;}

 task5

代码：#include <stdio.h>int main() {int a, b, c;while (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");continue;}if (a == b && b == c)printf("等边三角形\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 || a == c || b == c)printf("等腰三角形\n");elseprintf("普通三角形\n");}return 0;}

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 task6

代码：#include <stdio.h>#include <stdlib.h>#include <time.h>int main() {int lucky, guess, i;srand((unsigned)time(NULL));lucky = rand() % 30 + 1;printf("猜猜2026年4月哪一天是你的lucky day\n");for (i = 0; i < 3; i++) {if (i == 0)printf("开始喽，你有3次机会，猜吧(1~30)：");elseprintf("再猜(1~30)：");scanf("%d", &guess);if (guess == lucky) {printf("哇，猜中了:)\n");return 0;} else if (guess > lucky)printf("你猜的日期晚了，你的lucky day在前面哦\n");elseprintf("你猜的日期早了，你的lucky day还没到呢\n");}printf("次数用光啦。4月你的lucky day是%d号\n", lucky);return 0;}

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