Linker Problems with XCode

Hello everyone! I’ve got a problem.
Here is my
1)main.cpp: https://pastebin.com/Win3cr6b
2)FBullCowGame.cpp: https://pastebin.com/wNdY1rvf
3)FBullCowGame.h: https://pastebin.com/x9fR78d4

I try to compile, but it fails with the following message:
$ g++ -std=c++11 main.cpp
Undefined symbols for architecture x86_64:
“FBullCowGame::GetMaxTries()”, referenced from:
PlayGame() in main-f92a5a.o
“FBullCowGame::GetCurrentTry()”, referenced from:
GetGuess() in main-f92a5a.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I’ve already tried:
-to rewrite the whole code
-to google this error
But it didn’t help!

Thank you in advance!!!

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