I am new to Xcode and when I build the following code (an MWE), I get the following error
ld: 3 duplicate symbols for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)
I have three files as following;
main.cpp
#include "B.cpp"
int main() {
square(5);
return 0;
}
B.cpp
#include "A.cpp"
void square(int n){
display(n*n);
}
A.cpp
#include <iostream>
using namespace std;
void display(int num){
cout<<num;
}
I have tried different methods mentioned on stack overflow like change "Build Active Architecture Only" to "Yes" and some others but the error still persists.
duplicate symbol _OBJC_IVAR_$_BLoginViewController._hud in: 17 duplicate symbols for architecture x86_64. "Means that you have loaded same functions twice. As the issue disappear after removing -ObjC from Other Linker Flags, this means that this option result that functions loads twice:"
Why Is the Undefined Symbols for Architecture x86_64: Error Happening? This error is happening due to the lack of included values inside the declared statements in your code. The browser is going to render the information incorrectly and show this error, especially if you are working with Main and Similarity tools.
Problem is that main.cpp
has included B.cpp
and A.cpp
. In your build process, you are also compiling B.cpp
and A.cpp
and trying to link B.o
and A.o
alongwith main.o
.
Linking B.o
and A.o
causes symbols display
and square
to be defined multiple times. display
is defined 3 times and square
defined 2 times.
You just compile and build main.cpp
. Do not build A.cpp
and B.cpp
.
Second way is that make A.cpp
and B.cpp
to A.h
and B.h
and functions inline
. So, they will be compiled only once.
Third way, do not include B.cpp
in main.cpp
. Just put function declaration instead of inclusion.
//main.cpp
void square(int);
int main() {
square(5);
return 0;
}
Generally, function declarations are put in header files. If that is required in multiple cases, make a header file.
For me, changing 'No Common Blocks' from Yes to No ( under Targets->Build Settings->Apple LLVM - Code Generation ) fixed the problem.
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