std::filesystem copy_file failure

Question

I am trying to make a copy of a file.

This code runs without error, but the copied file is incomplete:

#include <iostream>
#include <filesystem>

using namespace std;

int main()
{
    error_code ec;
    filesystem::copy_file(
        "C:/ProgramData/spectronix/oximeter/spectrumalpha.dat",
        "C:/ProgramData/spectronix/oximeter/test.dat", ec );
    cout << ec.value() << "\n";
    return 0;
}

sample run:

C:\ProgramData\spectronix\oximeter>dir
 Volume in drive C is OS
 Volume Serial Number is 86AE-5DBA

 Directory of C:\ProgramData\spectronix\oximeter

2020-04-03  04:36 PM    <DIR>          .
2020-04-03  04:36 PM    <DIR>          ..
2020-04-03  01:29 PM            24,576 spectrum.dat
2020-03-23  12:27 PM           131,072 spectrumalpha.dat
2020-04-03  04:36 PM           963,072 test.exe
               3 File(s)      1,118,720 bytes
               2 Dir(s)  823,148,593,152 bytes free

C:\ProgramData\spectronix\oximeter>test
0

C:\ProgramData\spectronix\oximeter>dir
 Volume in drive C is OS
 Volume Serial Number is 86AE-5DBA

 Directory of C:\ProgramData\spectronix\oximeter

2020-04-03  04:37 PM    <DIR>          .
2020-04-03  04:37 PM    <DIR>          ..
2020-04-03  01:29 PM            24,576 spectrum.dat
2020-03-23  12:27 PM           131,072 spectrumalpha.dat
2020-04-03  04:37 PM             7,409 test.dat
2020-04-03  04:36 PM           963,072 test.exe
               4 File(s)      1,126,129 bytes
               2 Dir(s)  823,148,515,328 bytes free

Notice that the original file has 131,072 bytes, but the copied file only has 7,409 bytes.

You are clearly running the code on Windows. Do you have the same problem using the Win32 [`CopyFile()`](https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-copyfile) function instead? — Remy Lebeau, Apr 03 '20 at 20:51
This looks like the copy-a-binary-file-as-text problem (where the first EOF character ends the copy), but `copy_file` isn't supposed to care about that. — 1201ProgramAlarm, Apr 03 '20 at 20:59
You should try updating your compiler or using the visual studio compiler, the mingw compiler seems to have a few issues with std::filesystem on Windows — Alan Birtles, Apr 03 '20 at 21:02

std::filesystem copy_file failure

0 Answers0