GetFileSize

Windows API Reference

Function

GetFileSize determines the size of a specified file.

Syntax


DWORD GetFileSize(
  [in] HANDLE  hFile,
  [out] LPDWORD lpFileSizeHigh
);

Parameters

Parameter Type Description
hFile HANDLE A handle to the file whose size is to be retrieved. The handle must have been created with the GENERIC_READ access right.
lpFileSizeHigh LPDWORD A pointer to a DWORD variable that receives the high-order 32 bits of the file size. This parameter can be NULL if the file size fits within the low-order 32 bits.

Return Value

If the function succeeds, the return value is the low-order 32 bits of the file size. If the file size is greater than 4 GB, the return value is INVALID_FILE_SIZE and the high-order bits are returned in the buffer pointed to by lpFileSizeHigh.

If the function fails, the return value is INVALID_FILE_SIZE and GetLastError is set to an appropriate error code.

Remarks

To get the size of a file, you typically use the GetFileSizeEx function. The GetFileSize function is provided for compatibility with earlier versions of Windows.

The lpFileSizeHigh parameter is used to retrieve file sizes larger than 4 GB. If lpFileSizeHigh is not NULL, the high-order 32 bits of the size are returned in the DWORD value pointed to by lpFileSizeHigh. The low-order 32 bits are returned by the function.

If the file size is less than 4 GB, the value returned in lpFileSizeHigh is usually 0.

The INVALID_FILE_SIZE return value is a 32-bit value, which is 0xFFFFFFFF. Because file sizes are unsigned, a return value of INVALID_FILE_SIZE is not a possible file size.

Example

Show C++ Example

#include <windows.h>
#include <iostream>

int main() {
    HANDLE hFile = CreateFile(
        L"example.txt",           // File name
        GENERIC_READ,             // Access mode
        FILE_SHARE_READ,          // Share mode
        NULL,                     // Security attributes
        OPEN_EXISTING,            // Creation disposition
        FILE_ATTRIBUTE_NORMAL,    // Flags and attributes
        NULL                      // Template file
    );

    if (hFile == INVALID_HANDLE_VALUE) {
        std::cerr << "Error creating file handle: " << GetLastError() << std::endl;
        return 1;
    }

    DWORD fileSizeLow = GetFileSize(hFile, NULL);
    if (fileSizeLow == INVALID_FILE_SIZE) {
        std::cerr << "Error getting file size: " << GetLastError() << std::endl;
        CloseHandle(hFile);
        return 1;
    }

    std::cout << "File size (low 32 bits): " << fileSizeLow << " bytes" << std::endl;

    DWORD fileSizeHigh = 0;
    fileSizeLow = GetFileSize(hFile, &fileSizeHigh);
    if (fileSizeLow == INVALID_FILE_SIZE) {
        std::cerr << "Error getting file size (high bits): " << GetLastError() << std::endl;
        CloseHandle(hFile);
        return 1;
    }

    if (fileSizeHigh > 0) {
        std::cout << "File size (high 32 bits): " << fileSizeHigh << " bytes" << std::endl;
        std::cout << "Total file size: " << (static_cast<ULONGLONG>(fileSizeHigh) << 32) + fileSizeLow << " bytes" << std::endl;
    }

    CloseHandle(hFile);
    return 0;
}

Requirements
Minimum supported client Windows 2000 Professional
Minimum supported server Windows 2000 Server
Header fileapi.h (include windows.h)
Library Kernel32.lib
DLL Kernel32.dll

See Also