获取文件CRC32值VC++实现。。。。。

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首先在头文件里面申明一下： unsigned long Crc32Table[256];

代码开始：

void CGetCrcDlg::OnGetFileCrc() //打开文件然后在EDIT控件里面直接显示文件校验值；

{

HANDLE hFile = {NULL};

DWORD dwSize, bytes_read;

CString FileNameStr;

MakeTable();//生成码表

//打开对话框

CFileDialog dlg(TRUE, NULL, "", OFN_HIDEREADONLY,

"All Files (*.*)|*.*||", this);

if(IDOK != dlg.DoModal())

return;

FileNameStr = dlg.GetPathName();

hFile = CreateFile(FileNameStr, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE,

NULL, OPEN_EXISTING,

FILE_FLAG_SEQUENTIAL_SCAN, NULL);

dwSize = GetFileSize(hFile, NULL);

CString csData(' ', dwSize);

ReadFile(hFile, csData.GetBuffer(dwSize), dwSize, &bytes_read, NULL);

CloseHandle(hFile);

csData.ReleaseBuffer();

int nCRC = Get_CRC(csData, dwSize);

char ch[20];

itoa(nCRC, ch, 16);

m_FileCrcValue= ch;

m_FileCrcValue.MakeUpper();

UpdateData(FALSE);

}

void CGetCrcDlg::MakeTable()//动态生成CRC32的码表

{

int i,j;

unsigned long crc;

for (i = 0; i < 256; i++)

{

crc = i;

for (j = 0; j < 8; j++)

{

if (crc & 1)

crc = (crc >> 1) ^ 0xEDB88320;

else

crc >>= 1;

}

Crc32Table[i] = crc;

}

}

int CGetCrcDlg::Get_CRC(CString &csData, DWORD dwSize)//获取crc32值

{

ULONG crc(0xffffffff);

int len;

unsigned char* buffer;

len = dwSize;

buffer = (unsigned char*)(LPCTSTR)csData;

while(len--)

crc = (crc >> 8) ^ Crc32Table[(crc & 0xFF) ^ *buffer++];

return crc^0xffffffff;

}

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