error LNK2001 unresolved external symbol C

Question

Say I have this function called DoThis const char  abc  in a file called one cpp  So when I attempt to call this function from another function in a different source file  two cpp   I get the error  error LNK2001  unresolved external symbol  C     even though I used  include  one h  What would I do to fix this

User · Answer

Sounds like you are using Microsoft Visual C++. If that is the case, then the most possibility is that you don't compile your two.cpp with one.cpp (one.cpp is the implementation for one.h).

If you are from command line (cmd.exe), then try this first: cl -o two.exe one.cpp two.cpp

If you are from IDE, right click on the project name from Solution Explore. Then choose Add, Existing Item.... Add one.cpp into your project.

User · Answer

That means that the definition of your function is not present in your program  You forgot to add that one cpp to your program   What  to add  means in this case depends on your build environment and its terminology  In MSVC  since you are apparently use MSVC  you d have to add one cpp to the project    In more practical terms  applicable to all typical build methodologies  when you link you program  the object file created form one cpp is missing

[c++] error LNK2001: unresolved external symbol (C++)

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