实验二

1.随机生成一个1~100的数
2.保留四位小数
3.随机生成一个学号

1.重置金额
2.break终止整个循环
continue仅终止这个小循环并继续执行循环
3.没必要，default并非必须

`#define _CRT_SECURE_NO_WARNINGS

include<stdio.h>

int main() {
char a;
a=getchar();
switch (a) {
case'r':printf("stop!\n"); break;
case'g':printf("go go go\n"); break;
case'y':printf("wait a minute\n"); break;
default:printf("something must be wrong...\n"); break;
}

return 0;

}
`

`#define _CRT_SECURE_NO_WARNINGS

include<stdio.h>

int main() {
float max, min, sum=0;
float x,y;
max = 0;
min = 20000;
while (scanf("%f", &x)==1 && x != -1) {
y = x;
if (max < y)
max = y;
if (min > y)
min = y;
sum += 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;

}`

`#define _CRT_SECURE_NO_WARNINGS

include<stdio.h>

include<stdlib.h>

include<time.h>

int main(){
int luckday,guess;
int chance = 3;

srand(time(0));
luckday = rand() % 30 + 1;
printf("猜猜2025年4月哪一天是你的luck day\n");
printf("开始喽，你有三次机会，猜吧（1~30）：");
while (chance > 0) {
	scanf("%d", &guess);
	if (luckday > guess) {
		printf("你猜的日期早了，你的luck day还没到呢\n");
		chance -= 1;
	}else if (luckday < guess) {
		printf("你猜的日期晚了，你的luck day在前面哦\n");
		chance -= 1;
	}else {
		printf("哇，猜中了:)"); return 0;
	}if (chance > 0) {
		printf("再猜（1~30）");
	}
}
printf("次数用完啦，偷偷告诉你，你的lucky day是%d", luckday);

return 0;

}`

`#define _CRT_SECURE_NO_WARNINGS

include <stdio.h>

int main() {
int n, i, j;
printf("input n: ");
scanf("%d", &n);
for (i = n; i >= 1; i--) {
for (j = 0; j < (n - i) * 2; j++) {
printf(" ");
}
for (j = 0; j < i; j++) {
printf(" O ");
}
printf("\n");
for (j = 0; j < (n - i) * 2; j++) {
printf(" ");
}
for (j = 0; j < i; j++) {
printf(" ");
}
printf("\n");
for (j = 0; j < (n - i) * 2; j++) {
printf(" ");
}
for (j = 0; j < i; j++) {
printf("I I ");
}
printf("\n");
}
return 0;
}`


（要截止了才发现与原题不一样，回头改好了再编辑一下）