How to get file size for Huge file(10GB) in c ?-CodePudding

I tried to get file size for 16 GB txt file. but I got different size with real size. who can help me?

HANDLE FileHandle = INVALID_HANDLE_VALUE;
long long FileSize;
FileHandle = CreateFileA(szInputFileName, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, NULL, NULL);
if(FileHandle == INVALID_HANDLE_VALUE)
    return;

FileSize = GetFileSize(FileHandle, NULL);

CodePudding user response：

As you can see in the GetFileSize documentation:
If the file size exceeds 32bit, you must provide the 2nd argument, to be filled with the 32 high bits of the size.
Then you can combine the 2 in order to get the final file size.

Code example:

HANDLE FileHandle = INVALID_HANDLE_VALUE;
// ... (initialize FileHandle)

DWORD FileSizeLow;
DWORD FileSizeHigh;
//------------------------------------vvvvvvvvvvvvvv-
FileSizeLow = GetFileSize(FileHandle, &FileSizeHigh);
uint64_t FileSize = ((uint64_t)FileSizeHigh << 32)   FileSizeLow;
// ...

Alternatively, as @IInspectable commented, you can use GetFileSizeEx:

LARGE_INTEGER FileSizeL;
if (GetFileSizeEx(FileHandle, &FileSizeL))
{
    LONGLONG FileSize = FileSizeL.QuadPart;  // 64bit signed
    // ...
}
else
{
    // Handle error ...
}

CodePudding user response：

The GetFileSize documentation recommends using GetFileSizeEx instead which is simpler:

LARGE_INTEGER FileSize;
if (!GetFileSizeEx(FileHandle, &FileSize))
{
  std::cout << "error getting file size\n";
}
else
{
  std::cout << "file size: " << FileSize.QuadPart << "\n";
}

for a more c solution std::filesystem::file_size (though this only works with a path, not a handle):

auto FileSize = std::filesystem::file_size(szInputFileName)

CodePudding user response：

With using this code, I could get over 10GB of file size successfully.

unsigned long long GetFileSize1(char* path)
{
    std::ifstream fstrm(path, ios_base::in | ios_base::binary);
    fstrm.seekg(0, ios_base::end);
    long long filesize = fstrm.tellg();
    return filesize;
}