ld: 1 duplicate symbol for architecture x86_64

问题:

I'm very very new to C and C++ programming, and have very little experience in Software Programming (my background is Web Based) But I'm trying to experiment with C / C++ and Xcode... So I've found this code (and many similar variations online):

#include <stdio.h>

int main()
{
    printf ("Test");
    return 0;
}

Yet when I come to compile it in Xcode I get the following error:

> duplicate symbol _main in:
>     /Users/thomas/Library/Developer/Xcode/DerivedData/test-etqojvxbxhxjqeggdzkbfufvbeza/Build/Intermediates/test.build/Debug/test.build/Objects-normal/x86_64/first.o
>     /Users/thomas/Library/Developer/Xcode/DerivedData/test-etqojvxbxhxjqeggdzkbfufvbeza/Build/Intermediates/test.build/Debug/test.build/Objects-normal/x86_64/main.o
> ld: 1 duplicate symbol for architecture x86_64 clang: error: linker
> command failed with exit code 1 (use -v to see invocation)

Maybe Xcode is the wrong thing for me to be using as a newbie? If anyone could recommend a better compiler, that would be great too!

回答1:

When you create a new project in Xcode, it automatically gives you a starting file with main() in it. If you created a new file, such as first.c, and then pasted your test code into it, you'll be defining main() twice, and getting that error.

You need to either delete the file (such as main.c, or main.m) that Xcode provides in your new project, or cut and paste your sample code into that file, instead of creating a new one.