{
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
	int arr[3][5] = { {1,2,3},{2,5,60},{1} };
	for (int a = 0; a < 3; a++)
{for(int b=0;b<5;b++)
	printf("%d\n", arr[a][b]);//二维数组
	}
	return 0;
}



```c

```c
在这里插入代码片

数组arr1与arr2内容的交换

{
{
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<windows.h>
    char arr1[] = "welcome to bit!!!!!";
	char arr2[] = "*******************";
	
	size_t left = 0;
	size_t right = strlen(arr1)-1;

	while (left<=right)
	{
		arr2[left] = arr1[left];
	arr2[right] = arr1[right];
		
		left++;
		right--;
		printf("%s\n", arr2);
		Sleep(1000);//休眠，单位是毫秒
		system("cls");//引用#include<windows.h>的库函数
	}
	printf("%s\n", arr1);

	return 0;}
}

二分查找在有序的数组中，查找指定的数值
//升序                   
//[1 2 3 4 5 6 7 8 9 10]

int main()
{
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int k = 7;
	int i = 0;
	int sz = sizeof(arr) / sizeof(arr[0]);
	for (i = 0; i < sz; i++)
	{
		if (arr[i] == k)
		{
			printf("找到了，下标是:%d\n", i);
		break;
		}
	}
if (i == sz)
		printf("找不到\n");

	return 0;
}

int main()
{
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int k = 0;
	scanf("%d", &k);
	int sz = sizeof(arr) / sizeof(arr[0]);

	int left = 0;
	int right = sz - 1;

	while (left<=right)
	{
		int mid = (left + right) / 2;//被查找范围的中原元素的下标
	if (arr[mid] < k)
		{
			left = mid + 1;		}
	else if (arr[mid] > k)
		{
			right = mid - 1;
	}
		else
	{
		printf("找到了，下标是:%d\n", mid);
	break;
	}
	}
	if (left > right)
		printf("找不到了\n");

	return 0;
}

int main()
{
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int k = 0;
	scanf("%d", &k);
	int sz = sizeof(arr) / sizeof(arr[0]);

	int left = 0;
	int right = sz - 1;

	int flag = 0;//假设找不到
	while (left <= right)
	{
		int mid = (left + right) / 2;//被查找范围的中原元素的下标
		if (arr[mid] < k)
		{
			left = mid + 1;
		}
		else if (arr[mid] > k)
		{
			right = mid - 1;
		}
		else
		{
			printf("找到了，下标是:%d\n", mid);
			flag = 1;//找到了
			break;
		}
	}
	if (flag == 0)
		printf("找不到了\n");

return 0;
}