走刀口

在使用CFileDialog类打开文件中，若要同时选择多个文件，需要设置OFN_ALLOWMULTISELECT属性，如下代码所示：
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CFileDialog fileDlg(true, NULL, NULL, OFN_ALLOWMULTISELECT);
fileDlg.m_ofn.lpstrFilter = _T("ZV File(*.zv)\0 *.zv\0MPG File(*.mpg)\0 *.mpg\0MPEG4 File(*.mpeg4)\0 *.mpeg4\0H264 File(*.264)\0 *.264\0All File(*.*)\0 *.*\0");
if (IDOK == fileDlg.DoModal())
{
POSITION pos = fileDlg.GetStartPosition();
while(pos)
{
CString strPathName = fileDlg.GetNextPathName(pos);
AfxMessageBox(strPathName);
}
}
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但在实际使用过程中，如何同时选择的文件过多，fileDlg.GetNextPathName(pos)返回的文件名不正确，获取到的错误号为FNERR_BUFFERTOOSMALL，即缓存太小。

在MSDN关于CFileDialog多文件的描述中则说明了这种情况
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When the user allocates their own buffer to accommodate OFN_ALLOWMULTISELECT, the buffer cannot be larger than 2048 or else everything gets corrupted (2048 is the maximum size).

Additionally, you must set m_ofn.nMaxFile with the number of characters in the buffer pointed to by m_ofn.lpstrFile. If you set the maximum number of files to be selected to n, the necessary buffer size is n*(_MAX_PATH + 1) + 1. For example:
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CFileDialog dlgFile(TRUE);
CString fileName;
const int c_cMaxFiles = 100;
const int c_cbBuffSize = (c_cMaxFiles * (MAX_PATH + 1)) + 1;
dlgFile.GetOFN().lpstrFile = fileName.GetBuffer(c_cbBuffSize);
dlgFile.GetOFN().nMaxFile = c_cMaxFiles;

dlgFile.DoModal();
fileName.ReleaseBuffer();
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也就是说需要重新指定缓存大小，如果最大文件数量是100，那么缓存大小为100 * (MAX_PATH + 1) + 1，需要改变m_ofn中lpstrFile及nMaxFile的值，经调试发现m_ofn的nMaxFile默认大小为260。上述代码修改后为：
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CFileDialog fileDlg(true, NULL, NULL, OFN_ALLOWMULTISELECT);
int nMaxFiles = 2600; //修改此处大小容纳更多文件
int nBuffSize = (nMaxFiles * (MAX_PATH + 1)) + 1;
fileDlg.m_ofn.nMaxFile = nMaxFiles;
char* fileBuff = new char[nBuffSize];
memset(fileBuff, 0, sizeof(fileBuff));
fileDlg.m_ofn.lpstrFile = (LPWSTR)fileBuff;
fileDlg.m_ofn.lpstrFilter = _T("ZV File(*.zv)\0 *.zv\0MPG File(*.mpg)\0 *.mpg\0MPEG4 File(*.mpeg4)\0 *.mpeg4\0H264 File(*.264)\0 *.264\0All File(*.*)\0 *.*\0");

if (IDOK == fileDlg.DoModal())
{
//m_strSrcFile = dlg.GetPathName();
POSITION pos = fileDlg.GetStartPosition();;
while(pos)
{
CString strPathName = fileDlg.GetNextPathName(pos);
AfxMessageBox(strPathName);
}
}
delete[] fileBuff;
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