c语言（8.6）

今天练习了几个小代码

#include<stdio.h>

void order(int arr[], int len);
int main()
{
	int arr[] = { 3,5,2,1,4 };
	int len = sizeof(arr) / sizeof(int);

	order(arr, len);

	for (int i = 0; i < len; i++)
	{
		printf("%d\n", arr[i]);
	}

	return 0;
}
void order(int arr[], int len)
{
	for (int i = 0; i < len - 1; i++)
	{
		for (int j = 1; j < len - i; j++)
		{
			if (arr[j] < arr[j - 1])
			{
				int temp = arr[j];
				arr[j] = arr[j - 1];
				arr[j - 1] = temp;


			}
		}
	
	}



}

#include<stdio.h>
int binsearch(int arr[], int len, int num);
int main()
{
	int arr[] = { 7,23,79,81,103,127,131,147 };
	int len = sizeof(arr) / sizeof(int);

	int num = 131;

	int index = binsearch(arr, len, num);
	printf("%d\n", index);

	return 0;
}
int binsearch(int arr[], int len, int num)
{
	int max = len - 1;
	int min = 0;
	//mid得写在循环里面
	while (min <= max)
	{
		int mid = (min + max) / 2;
		if (num > arr[mid])
		{
			min = mid + 1;
		}
		else if (num < arr[mid])
		{
			max = mid - 1;
		}
		else
		{
			return mid;
		}
	}

	return -1;

}

#include<stdio.h>
int order(int arr[], int len, int num);
int main()
{
	int arr[] = { 11,22,55,77,44 };
	int len = sizeof(arr) / sizeof(int);

	int num = 55;

	int index = order(arr, len, num);

	printf("%d\n", index);


	return 0;
}
int order(int arr[], int len, int num)
{
	//从头到尾全部检查过一遍后，如果没有，才能返回-1
	for (int i = 0; i < len; i++)
	{
		if (arr[i] == num)
		{
			return i;
		}
	}
	//else不能写在里面，和昨天写的代码类似
	return -1;

}

#include<stdio.h>
#include<stdlib.h>
#include<time.h>

void printArr(int arr[], int len);
int main()
{
	int arr[] = { 1,2,3,4,5 };
	int len = sizeof(arr) / sizeof(int);

	printArr(arr, len);
	for (int i = 0; i < len; i++)
	{
		srand(time(NULL));
		int index = rand()%5;
		
		int temp = arr[i];
		arr[i] = arr[index];
		arr[index] = temp;
	
	}
	
	printArr(arr,len);



	return 0;
}
void printArr(int arr[], int len)
{
	for (int i = 0; i < 5; i++)
	{
		printf("%d\n", arr[i]);
	}

}