C++ 文件大小格式化

#include <iostream>
#include <windows.h>
using namespace std;

/*文件大小格式化
 *param [in] dwSize   xx.xxB 、xx.xxKb 、xx.xxM
 */

LPCTSTR CFileUtil::FileSizeToFormat(DWORD dwSize)
{
    TCHAR* strSize = new TCHAR[20];
    ZeroMemory(strSize,sizeof(TCHAR) * 20);

    double i = pow((double)2,10);

    if (dwSize < pow((double)2,10))//dwSize < 1024
    {
        _stprintf_s(strSize,20,TEXT("%dB"),dwSize);//文件大小 B
    }
    else if (pow((double)2,10) <= dwSize &&  dwSize< pow((double)2,20))// 1024 <= dwSize < 1024*1024
    {
        float fSize = (float)(dwSize*100/1024)/100;
        _stprintf_s(strSize,20,TEXT("%.2fKB"),fSize);
    }
    else if (pow((double)2,20) <= dwSize && dwSize < pow((double)2,30))// 1024*1024 <= dwSize < 1024*1024*1024
    {
        float fSize = (float)(dwSize/1024*100/1024)/100;
        _stprintf_s(strSize,20,TEXT("%.2fM"),fSize);//文件大小 M
    }
    else if (pow((double)2,30) <= dwSize && dwSize < pow((double)2,40)) // 1024*1024*1024 <= dwSize < 1024*1024*1024*1024
    {
        float fSize = (float)(dwSize/1024*100/1024/1024)/100;
        _stprintf_s(strSize,20,TEXT("%.2fG"),fSize);//文件大小 G 
    }
    else
    {
        float fSize = (float)(dwSize/1024*100/1024/1024/1024)/100;
        _stprintf_s(strSize,20,TEXT("%.2fT"),fSize);//文件大小 T
    }
    
    return strSize;
}

/*根据文件大小进行格式化
*@[in ]  llBytes    文件的长度(B)
*@[out]  pszSize    缓冲区
*@[in ]  clen       缓冲区长度
*/

BOOL FileSizeToStringA(LONGLONG llBytes, char* pszSize, DWORD cLen)
{
    double bytes = (double)llBytes;
    DWORD cIter = 0;    
    char* pszUnits[] = { ("B"), ("KB"), ("MB"), ("GB"), ("TB") };
    DWORD cUnits = sizeof(pszUnits) / sizeof(pszUnits[0]);

    // move from bytes to KB, to MB, to GB and so on diving by 1024
    while(bytes >= 1024 && cIter < (cUnits-1))
    {
        bytes /= 1024;
        cIter++;
    }
    _snprintf_s(pszSize, cLen, _TRUNCATE,("%.2f %s"), bytes, pszUnits[cIter]);
    return TRUE;
}

int main()
{
    char szText[256];
    FileSizeToStringA(23156,szText,256);

    cout << "szText:" << szText << endl;

    getchar();
    return 0;
}