c++ ——基本排序（选择排序，交换排序，冒泡排序，插入排序）

void selection(int *a, int length)//选择排序
{
	for (int i = 0; i < length - 1; i++)
	{
		int pass = i;
		for (int j = i + 1; j < length; j++)
			if (*(a + pass) < *(a + j))
				pass = j;
		if (pass != i)
		{
			int temp = *(a + i);
			*(a + i) = *(a + pass);
			*(a + pass) = temp;
		}
	}
}
void exchange(int *a, int length)//交换排序
{
	for (int i = 0; i < length - 1; i++)
	{
		for (int j = i + 1; j < length; j++)
			if (*(a + i) < *(a + j))
			{
				int temp = *(a + i);
				*(a + i) = *(a + j);
				*(a + j) = temp;
			}
	}
}
void bobble(int *a, int length)//冒泡排序
{
	
	for (int i = 1; i < length; i++)
	{
		bool exchange = 0;//哨兵
		for (int j = 0; j < length - i; j++)
			if (*(a + j) < *(a + j + 1))
			{
				int temp = *(a + j);
				*(a + j) = *(a + j + 1);
				*(a + j + 1) = temp;
				exchange = 1;
			}
		if (exchange == 0)
			break;
	}
}
void insert(int *a, int length)//插入排序
{
	for (int i = 1; i < length; i++)
	{
		int temp = *(a + i);
		for (int j = i - 1; j >= 0 && *(a + j) < temp; j--)
		{
			*(a + j + 1) = *(a + j);
			*(a + j ) = temp;
		}
	}
}