Question

I am creating a converter for quaternions to euler angles, I have written this code:

//(...)
/*
* Converter Includes
*/
#include "EulerAngles.h"
//(...)
static cell AMX_NATIVE_CALL n_QuatToEuler( AMX* amx, cell* params )
{
    Quat q;
    q.x = amx_ctof(params[1]);
    q.y = amx_ctof(params[2]);
    q.z = amx_ctof(params[3]);
    q.w = amx_ctof(params[4]);
    EulerAngles EU = Eul_FromQuat(q,params[5]);
    //(...)
    return 1;
}
//(...)

I included the EulerAngles.c from http://tog.acm.org/resources/GraphicsGems/gemsiv/euler_angle/ into my project, I also downloaded all the other files into my project.

When I try to compile my project I get these error messages from Visual Studio 2012:

Error   1   error LNK2001: unresolved external symbol "struct Quat __cdecl Eul_FromQuat(struct Quat,int)" (?Eul_FromQuat@@YA?AUQuat@@U1@H@Z)    .\calculatorSAMP\calculatorSAMP.obj calculatorSAMP
Error   2   error LNK1120: 1 unresolved externals   .\calculatorSAMP\Release\calculatorSAMP.dll calculatorSAMP

the QuadTypes.h which is included in EulerAngles.h has this code:

/**** QuatTypes.h - Basic type declarations ****/
#ifndef _H_QuatTypes
#define _H_QuatTypes
/*** Definitions ***/
typedef struct {float x, y, z, w;} Quat; /* Quaternion */
enum QuatPart {X, Y, Z, W};
typedef float HMatrix[4][4]; /* Right-handed, for column vectors */
typedef Quat EulerAngles;    /* (x,y,z)=ang 1,2,3, w=order code  */
#endif

What am I missing here?

I tried to edit it to:

/**** QuatTypes.h - Basic type declarations ****/
#ifndef _H_QuatTypes
#define _H_QuatTypes
/*** Definitions ***/
struct Quat {float x, y, z, w;}; /* Quaternion */
enum QuatPart {X, Y, Z, W};
typedef float HMatrix[4][4]; /* Right-handed, for column vectors */
#define EulerAngles Quat ;    /* (x,y,z)=ang 1,2,3, w=order code  */
#endif

But it caused more errors.

Answer 1

If it is a .c file, it is compiled as C by default.

You either have to change the “compile as” option for that file, or add extern "C" to the declaration in the .h file.