1.二分法找数

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int arr[]={1,2,3,4,5,6,7,8,9,10};
	int k=7;
	int sz=sizeof(arr)/sizeof(arr[0]);//计算元素个数
	int left=0;//左下标
	int right=sz-1;//右下标
	while (left<=right)
	{
		int mid=(left+right)/2;
		if(arr[mid]>k)
		{
			right=mid-1;
		}
		else if (arr[mid] < k )
			{
				left=mid+1;
		}
		else
		{
			printf("找到了，下标为:%d\n",mid);
			break;
		}
	}
	if(left>right)
		{
			printf("找不到\n");
		}
		return 0;
}

2.从两边向中间缓慢打印一串数

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<windows.h>
#include<stdlib.h>
int main()
{
	char arr1[]="wo shi ni die!!!!!";
	char arr2[]="##################";
	int left=0;
	int right=strlen(arr1)-1;
	while(left<=right)
	{
		arr2[left]=arr1[left];
		arr2[right]=arr1[right];
		printf("%s\n",arr2);
		Sleep(1000);
		system("cls");
		left++;
		right--;
	}
	printf("%s\n",arr2);
	return 0;
	
}

3.简易验证密码

int main()
{
	int i=0;
	char password[20]={0};
	for(i=0;i<3;i++)
	{
		printf("请输入密码:");
		scanf("%s",password);
		if(strcmp(password,"123456")==0)
		{
			printf("登录成功\n");
			break;
		}
		else{printf("密码错误\n");}
	}
	if (i==3)
		printf("三次密码均错误\n");
	return 0;
}