实验二

实验任务一
`#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));

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：代码的作用是生成随机数，去掉代码输出结果相同
问题2：生成五个给定要求的随机数

实验任务2
`#include <stdio.h>

int main(){
int choice, quantity;
float total_price = 0, amount_paid, change;

while(1) {
	printf("\n自动饮料售货机菜单：\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：\n");
	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：去掉之后total_price不会重置，下一次输入total_price不为0
问题2：continue的作用是结束本次循环并进入下一次循环

实验任务3
#include <stdio.h> int main() { char sign; while (scanf("%c", &sign) != EOF) { getchar (); if(sign == 'r') { printf("stop"); } else if(sign == 'g') { printf("go go go\n"); } else if(sign == 'y') { printf("wait a minute\n"); } else { printf("something must be wrong...\n"); } } return 0; }

实验任务4
#include <stdio.h> int main() { float expend, total = 0, max = 0, min = 20000; while(1) { scanf("%f", &expend); if(expend == -1) { break; } total += expend; if(expend > max) { max = expend; } if(expend < min) { min = expend; } } printf("今日累计消费总金额：%.1f\n", total); 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; }

实验任务5
#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"); }else { if(a == b && b == c) { printf("等边三角形\n"); } else if(a == b || a == c || b == c ) { 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; }#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"); }else { if(a == b && b == c) { printf("等边三角形\n"); } else if(a == b || a == c || b == c ) { 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; }

实验任务6
`#include <stdio.h>

include <stdlib.h>

include <time.h>

int main() {
srand(time(NULL));
int answer = rand()%30 + 1;
int guess;
printf("猜猜2025年11月哪天是你的lucky day");
printf("开始喽，你有三次机会，猜吧（1~30）：");
for(int i = 3; i >= 1; --i) {
if(i != 3)
printf("再猜（1~30）：");
scanf("%d", &guess);
if(guess == answer) {
printf("哇，猜中了:)");
break;
}
else if(guess > answer) {
printf("你猜的日期晚了，你的lucky day在前面哦");
}
else {
printf("你猜的日期早了，你的lucky day在后面哦");
}
}
if(guess != answer)
printf("次数用光啦。偷偷告诉你，11月你的lucky day是%d", answer);
return 0;
}`