MSVC build errors > C2039

C2039: is not a member of

error C2039: 'filesystem': is not a member of 'std'

The name after ., ->, or :: is not a member of that class or namespace, as far as the compiler knows at that point.

Causes and fixes

1. The member name is misspelled. Check the spelling and the case, for example push_back.
2. The header that declares it is not included. std::filesystem needs <filesystem>, std::optional needs <optional>: include the header of what you use.
3. The member needs a newer C++ standard. std::filesystem needs C++17, starts_with C++20: set C/C++ > Language > C++ Language Standard.
4. The member belongs to another class. The variable may have another type than you think, such as a pointer that needs ->, or a base class that does not declare the member.

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Related errors: C2065. See all guides.