Why Does Gcc Not Seem to Have the Filesystem Standard Library

Why does GCC not seem to have the filesystem standard library?

GCC v7 still does not implement <filesystem> but it does have the Filesystem Technical Specification which is in <experimental/filesystem>

#include <experimental/filesystem>

// for brevity
namespace fs = std::experimental::filesystem;

int main()
{
    fs::path p = "/path/to/my/file"; // etc...
}

This is also available in GCC v6.

To link with the library you need to add -lstdc++fs to the command line.

Note: There may be some minor differences between the current Technical Specification and the final draft of <filesystem> that is decided upon by the Standards Committee.

Note 2: GCC v8 now implements <filesystem> with the -std=c++17 flag.

how to use std::filesystem on gcc 8?

Add the filesystem library as an argument to your compiler that will be forwarded to the linker. Also make sure you are using C++17. Both g++ and clang++ accepts this particular format:

--std=c++17 -lstdc++fs

How can I install the filesystem C++ library with minGW?

The C++ filesystem library was introduced in C++17, but your compiler might be configured to use an earlier version of the language by default. Try using the -std=c++17 option.

Link errors using filesystem members in C++17

Add the flag -lstdc++fs:

$ g++-7 test.cpp -std=c++17 -lstdc++fs

gcc 7.2 supports C++17 experimental filesystem namespace only. I do not know, maybe gcc 7.3 supports std filesystem namespace already.

fatal error: filesystem: No such file or directory

It seems you have to include <filesystem> like this:

#include <experimental/filesystem>

Don't forget to add -lstdc++fs as a GCC flag!

Here is the proof:
Coliru

If that doesn't work, then that probably means that you don't have filesystem in your configuration.

Also, as @MartinR. pointed out, the experimental is no longer needed in GCC 8+.

std::filesystem example not compiling on c++ 17

There was a defect in C++17 standard that didn't allow operator<< to be called with std::filesystem::directory_entry, reported in LWG 3171. It's now fixed as defect report, but it seems clang only fixed it in version 14: https://godbolt.org/z/3arTcGYvY. gcc seems to have backported the fix to all versions that support std::filesystem (that is, gcc9.1 and up): https://godbolt.org/z/fh7cdMxso

c++ 17 std::filesystem can not run on other (windows 10) computer

Did you check that the

libstdc++-6.dll

Is available or the relevant libraries are statically included static linked libs

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