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工作总结:MFC自写排序算法(升序)

最近一个需求里面需要实IP升序排序,用了qsort,结果是内部排序,甚至感觉排序结果不可预测性,于是自己写了一个外部排序。

需求如下:一个指针里面有N条记录,每条记录包含:IP,偏移地址,保留位,均占4个字节,且这N条记录需要按照升序排序。

算法如下:

for (int i = 1; i < m_nCount; i++ )//sort
        {
            DWORD dwPre = NULL;//pCurAddr.GetIP()+i
            DWORD dwNex = NULL;
            char cTemp[12] = {0};
            char cTemp2[12] = {0};
            for (int j = m_nCount - 1; j >= i; j--)
            {
                memcpy(&dwPre, pLCIndexBuf+ ((j-1)*12), 4);
                memcpy(&dwNex, pLCIndexBuf+(j*12), 4);
                if (dwNex > dwPre)
                {
                    memcpy(&cTemp, pLCIndexBuf + (j*12), 12);
                    memcpy(&cTemp2, pLCIndexBuf + ((j-1)*12), 12);
                    memcpy(pLCIndexBuf + (j*12), cTemp2, 12);
                    memcpy(pLCIndexBuf + ((j-1)*12), cTemp, 12);
                }
            }
        }

 最后大家讨论,上述方法存在问题:

1.冒泡排序非最优,二分较好;

2.memcpy函数使DWORD类型IP倒序未做处理

最后还是用了qsort函数,上次使用qsort函数导致排序错误是由于下面黄色标记代码出错原因

代码如下:

qsort(&pLCIndexBuf[0], m_nCount, 12, CompareAMTIndexV6);

int CompareAMTIndexV6(const void *a,const void *b)
{
    //CAddr pCurAddr;
    DWORD pOne = *(DWORD*)a;
    DWORD pTwo = *(DWORD*)b;

    //first section of IP Address
    BYTE byTemp1 = LOBYTE(LOWORD(pOne));
    BYTE byTemp2 = LOBYTE(LOWORD(pTwo));
    if (byTemp1 != byTemp2) 
    {
        return ((int)byTemp1 - (int)byTemp2);
    }

    //Second section of IP Address
    byTemp1 = HIBYTE(LOWORD(pOne));
    byTemp2 = HIBYTE(LOWORD(pTwo));
    if (byTemp1 != byTemp2) 
    {
        return ((int)byTemp1 - (int)byTemp2);
    }

    //Third section of IP Address
    byTemp1 = LOBYTE(HIWORD(pOne));
    byTemp2 = LOBYTE(HIWORD(pTwo));
    if (byTemp1 != byTemp2) 
    {
        return ((int)byTemp1 - (int)byTemp2);
    }

    //Fourth section of IP Address
    byTemp1 = HIBYTE(HIWORD(pOne));
    byTemp2 = HIBYTE(HIWORD(pTwo));
    if (byTemp1 != byTemp2) 
    {
        return ((int)byTemp1 - (int)byTemp2);
    }

    return *(int*)a - *(int*)b;//升序
}