Xcode duplicate symbol error

Question

I am getting \"Apple Mach-O Linker (Id) Error\":

ld: duplicate symbol _matrixIdentity in /BlahBlah/Corridor.o and /Blahblah/Drawable.o for architecture i386
         


        

Answer 1

C/C++/Objective-C diff with Java, C#, Ruby, Python...

Divide files.

header & mm

Do not use #include (may include many times)

Use #import... (include once)

---

Utils.h

#ifndef __utils_h__ // <<< avoid multiple #include
#define __utils_h__ // <<< avoid multiple #include
#import     
...
#pragma mark -
#pragma mark Definitions

typedef float mat4[16];

#pragma mark -
#pragma mark Functions
extern void matrixIdentity(mat4 m);

#endif // __utils_h__ <<< avoid multiple #include

---

Utils.mm

#import "Utils.h"

void matrixIdentity(mat4 m)
{
m[0] = m[5] = m[10] = m[15] = 1.0;
m[1] = m[2] = m[3] = m[4] = 0.0;
m[6] = m[7] = m[8] = m[9] = 0.0;
m[11] = m[12] = m[13] = m[14] = 0.0;
}
...