Thread: Question about array declaration/use

I load a map from a file. I got it to work perfect thanks to Salem (^_^), that is the loading part works fine, and my game using the array works fine...... but only if I declare the array (it's global) like this:

Code:

byte Map[800] = {0};

if I declare it like this:

Code:

byte Map[800];

or

Code:

byte *Map = NULL;

(and then create it using new and delete it properly, of course)

then it doesn't work. What happens is that for some reason it has odd numbers in it. I don't think it has to do with the file loading code, because it loads the map fine if I add that = {0}; to the end.

What can I do to make the other two declarations work as well, and what's the main difference between byte Map[800] = {0}; and byte Map[800];? Even if I fill Map with zeros before loading it, it still creates problems...

sorry if this is a weird prob... thanks for any help...

OK, the total code isn't extremely long so I'll post it:

Code:

// Map declaration
byte MAP[800] = {0};

// Map loading code

void LoadWorld (const char* fn)
{
	FILE *f;
	if ((f = fopen(fn, "r")) == NULL)
		return; 

	for (int y = 0; y < MainMap.Height; ++y) {
		for (int x = 0; x < MainMap.Width; ++x) {
			int c;
			if (fscanf(f, "%d,", &c) == 1) {
			  MAP[(y * MainMap.Width) + x] = c;
			} else {
				if (feof(f))
					break;
			}
		}
	}

	fclose(f);
}

// code to get tile at y, x
inline byte GetTile (int y, int x) {
	return (MAP[(y * MainMap.Width) + x]);
}

// code where map generates error: "c" is unexpected value
#define MAP_PRIMARY_BLANK 254	// 254 id tiles == skip

void DrawMap (int mapID)
{
	for (int y = 0; y < 16; ++y) {
		for (int x = 0; x < 21; ++x) { // called 336 times
			int c = GetTile(Cam.tCamy+y,Cam.tCamx+x);
			if (c != MAP_PRIMARY_BLANK) {
				masked_blit (tileset[mapID], vscreen, 
					pTiles[c]->xLoc, pTiles[c]->yLoc,
					(x << 4) - (Cam.CamxOff),
					(y << 4) - (Cam.CamyOff), 16, 16);
			}
		}
	}
}

I don't think the problem would be in any of the other variables (CamxOff, tCamx,x,y,etc), because the only time c ever becomes a problem is when the initialization to 0 is taken off. I tried memset(MAP, 0, 800 * sizeof (byte)); and it didn't change anything.

= /

What's confusing me is the file loading code, because I don't think it has any effect that could cause the error.

If after I load the map, I set it all to zero (using memset, or a loop), it still brings up strange values in the map drawing code. But, if I add that = {0}; ... no problems...