Can't get code to work properly

jeonghyunhan

Member

Posts: 75
Joined: 2009.01

Post: #1

Jul 16, 2009 — 11:48 AM

I'm not entirely sure I'm doing this right.

Code:

typedef struct

    {

        int a[3];

    } SomeType;

SomeType lala;

- (void)setVertices:(SomeType)v :(int)x :(int)y :(int)z {

    v.a[0] = x;

    v.a[1] = y;

    v.a[2] = z;

}

- (void)test {

    [self setVertices:lala :1 :3 :5];

    printf("%i, %i, %i", lala.a[0], lala.a[1], lala.a[2]);

}

Shouldn't it be printing out 1, 3, and 5?
It prints out 0, 0, 0.
Any help on this matter

ThemsAllTook

Moderator

Posts: 1,552
Joined: 2003.10

Post: #2

Jul 16, 2009 — 12:07 PM

Nope. In the code you pasted, -setVertices:::: is modifying a local copy of a SomeType, since that's the way you're passing it. The SomeType in -test remains unaltered.

jeonghyunhan

Member

Posts: 75
Joined: 2009.01

Post: #3

Jul 16, 2009 — 12:24 PM

Is there anyway to fix it so that the values are assigned?
I have a different piece of code working fine but it's like this:

Code:

typedef float MapVertex[3];

typedef float MapTexCoord[2];

MapVertex mapVerticesLayer1[15000];

MapTexCoord mapTexCoords[15000];

MapVertex mapVerticesLayer2[15000];

MapTexCoord mapTexCoordsLayer2[15000];

- (void)setMapVertices:(MapVertex)v :(float)x :(float)y :(float)z {

    v[0] = x;

    v[1] = y;

    v[2] = z;

}

- (void)setMapTexCoords:(MapTexCoord)v :(float)x :(float)y {

    v[0] = x;

    v[1] = y;

}

This works fine but I cannot seem to "reset" it all back to 0 and I'm having problems debugging it with NSLog and printf, so I decided to change it around a bit.

EDIT:
Well, I moved the printf function inside of -setVertices and it seems like it works =/

ThemsAllTook

Moderator

Posts: 1,552
Joined: 2003.10

Post: #4

Jul 16, 2009 — 02:19 PM

jeonghyunhan Wrote:EDIT:
Well, I moved the printf function inside of -setVertices and it seems like it works =/

Of course, because you're printing out the function's local copy of the struct. It sounds like you may need to brush up on some C fundamentals. I'd give you the answer, but you're better off reaching it by your own understanding, since this would cripple you in future coding.

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