macOS Xcode Struct Help

It works with gcc in terminal but not with the xCode build?

What compiler switches did you use to compile in the terminal? Compare that to what Xcode uses. I suspect it is that prehaps Xcode uses stricter compiler switches. Not sure, never really had a look at the default compiler options for Xcode.

It looks like Xcode is using the default C convention where typedef names are not automatically generated for struct tags (http://c-faq.com/struct/impltypedef.html)

That is in your application code, include the struct keyword:

struct Point *head= new Point;
struct Point *point= head;

Alternatively, keep the application code as is, but use a typedef in the header, for example:

#define dVec Vector<double>

typedef struct Point *PointPTR;

struct Point{
dVec xy;
PointPTR *next;
};

The typedef is necessary for reasons explained here: http://c-faq.com/decl/selfrefstruct.html

ScKaSx said:

Help!

Click to expand...

You probably need to change the type name you use. Types coming from the OS are usually a bad idea to override in practice.

It turns out the Point struct that's giving you trouble is defined as part of the old QuickDraw API (we're talking Mac OS 9 here). Somewhere, Xcode is configured to pull this in. You can view it here:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/CarbonCore.framework/Versions/A/Headers/MacTypes.h

(incidentally, spotlight didn't find this..I had to do a 'locate MacTypes.h' in the terminal)

This is an instance of the namespace management issue. You could either simply change the name of your Point type (e.g. to MyPoint), or else (assuming you're using C++) wrap your declaration of Point into a unique namespace, for example:

//Point.h
namespace foo
{
struct Point {...}
}

and either preface Point's usage in the .cpp file with the namespace or use the 'using namespace' directive

//Point.cpp
#include "Point.h"

foo:oint *head;
using namespace foo;
Point *point;

Get rid of the "using" declarations and just refer to

Points:oint

anywhere you need to reference your structure. The using keyword is dangerous (especially in header files) and reintroduces the ambiguity you're trying to resolve by putting your Point into its own namespace.

http://www.gotw.ca/publications/migrating_to_namespaces.htm

I'd also dispense with the all inline declarations (even though the compiler is free to ignore them). The above poster included a link to Herb Sutter's guru of the week blog, if you read the wisdom dispensed therein and other places, you'll find a thorough discussion of inline declarations and how they entangle dependencies....