实验二

task1

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define N 5
int main()
{
	int grade, number;
	int i;
	srand(time(0));

	for (i = 0;i < N;++i)
	{
		grade = rand() % 4 + 2018;
		number = rand() % 999 + 1;
		printf("%d833 %04d\n", grade, number);
	}
	return 0;
}

task2

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 3
int main()
{
	int ld, d, i, n = 0;
	srand(time(0));
	ld = rand() % 30 + 1;

	printf("猜猜2022年4月哪一天会是你的lucky day\n\n");
	printf("开始喽，你有三次机会，猜吧(1^30)：");
	for (i = 0; i < N; ++i)
	{
		scanf_s("%d", &d);
		if (d == ld)
		{
			printf("\n哇，猜中了:-)\n"); break;
		}

		if (d > ld)
		{
			printf("\n你猜的日期晚了，你的lucky day已经过啦\n");
		}
		else
		{
			printf("\n你猜的日期早了，你的lucky day 还没到呢\n");
		}
		n++;

		if (n < N)
		{
			printf("\n再猜(1^30)：");
		}
		else
		{
			printf("\n次数用完啦。偷偷告诉你：4月，你的lucky day是%d号\n", ld);
		}

	}
	return 0;
}

问题1：解释line16代码的功能
答：随机生成2018-2021范围内的数。

问题2：解释line17代码的功能
答：随机生成1-999范围内的数。

问题3：这个程序的功能是什么？
答：随机生成五个201883300001-202183300999内的数（随机生成五个2018级到2021级学生的学号）。

task3

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	char c;
	while (scanf("%c", &c) != EOF)
	{
		if (c == 'y')
		{
			printf("wait a minute\n");
		}

		else if (c == 'g')
		{
			printf("go go go\n");
		}

		else if (c == 'r')
		{
			printf("stop!\n");
		}

		else
		{
			printf("something must be wrong...\n");
		}

	c = getchar();
	}
	return 0;
}

task4

#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main()
{
	int n, a;
	double i, s, b;
	while (scanf("%d%d", &n, &a) != EOF)
	{
			for (s = 0, b = 0, i = 1; i <= n; i++)
		{
			b = b + a * pow(10, i - 1);
			s += i / b;
		}

		printf("n=%d,a=%d,s=%f\n\n", n, a, s);
	}
	system("pause");
	return 0;
}

task5

#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main()
{
	int n, a;
	double i, s, b;
	while (scanf("%d%d", &n, &a) != EOF)
	{
		for (s = 0, b = 0, i = 1; i <= n; i++)
		{
			b = b + a * pow(10, i - 1);
			s += i / b;
		}

		printf("n=%d,a=%d,s=%f\n\n", n, a, s);
	}
	system("pause");
	return 0;

}

task6_1

#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int n, N;
int main()
{
	printf("input n：");
	scanf("%d", &N);
	do
	{
		printf(" o \n");
		printf("<H>\n");
		printf("I I\n");
		printf("\n");
		n++;
	} while (n <= N);

	return 0;
}

task6_2

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	int n, N;
	printf("input n:");
	scanf("%d", &N);

	for (n = 1; n <= N; n++)
		printf(" o\t");
	printf("\n");

	for (n = 1; n <= N; n++)
		printf("<H>\t");
	printf("\n");

	for (n = 1; n <= N; n++)
		printf("I I\t");
	printf("\n");

	return 0;
}

task6_3

#define  _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int N, m, n, a;
	printf("input n：");
	scanf("%d", &N);
	for (m = 0; m <= N; m++)
	{
		for (n = 0; n <= m; n++)
			printf("\t");
		for (a = 0; a < N * 2 + 1 - m * 2; a++)
			printf(" o \t");
		printf("\n");

		for (n = 0; n <= m; n++)
			printf("\t");
		for (a = 0; a < N * 2 + 1 - m * 2; a++)
			printf("<H>\t");
		printf("\n");

		for (n = 0; n <= m; n++)
			printf("\t");
		for (a = 0; a < N * 2 + 1 - m * 2; a++)
			printf("I I\t");
		printf("\n");
	}
	return 0;
}