Parsing comma delimited integers to an array

[ichigo_cool]

I'm working on a map editor and the tiles show up i a file as

1, 0, 0, 1,
1, 0, 1, 1

so here's a 4x2 map. I'm wondering how can I parse out the integers from the commas and assign them to a multidimensional array so that \i can move onto drawing the tiles to the screen...
Thanks for any help!

[Narue]

Read an int, then ignore a single character. Optionally peek to see if the character is a comma for more robust error checking:

for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 4; j++) {
        if (!(in>> a[i][j]))
            break;
        in.ignore();
    }
}

[Old Doctor Ed]

whatever happened to strtok() lol

[Narue]

whatever happened to strtok() lol

Why complicate matters when you don't have to?

lol :icon_rolleyes:

[Lerner]

I would have thought that using this input:

1,

with this syntax:

fin >> a[j];

where a[j] is an int would result in fin going into an error state and that the stream would need to be reset/clearred before the char, the comma, that caused the error could be ignored. Guess I'll have to check it out when I get a compiler available.

I would have expected the posted syntax to work if the input had been:

1 , 0 , etc.

I would have used getline() with comma as the delimiter and then convert the input string into the desired numerical value using a stringstream; but, as I'm fond of saying, live and learn.

[Narue]

I would have thought that using this input:

1,

with this syntax:

fin >> a[j];

where a[j] is an int would result in fin going into an error state

Nope, input simply stops at the first non-integer character. The stream state isn't affected.

I would have expected the posted syntax to work if the input had been:

1 , 0 , etc.

Actually, that would not have worked without an extra step of trimming leading whitespace before extracting the comma. Leading whitespace after the comma is fine because operator>> will skip it automatically when reading an integer. Only the bogus integer character (a comma) needs to be removed.

I would have used getline() with comma as the delimiter and then convert the input string into the desired numerical value using a stringstream

Once again, why make it harder than it needs to be? :)

[ichigo_cool]

Narue, thank you! Your solution helped greatly and this works. I'm just wondering, is this the neat and proper way to do what you're explaining?

const int TILE_X = 4;
const int TILE_Y = 4;

int map_tiles[TILE_X][TILE_Y];
	
	//storing map data in map_tiles
	ifstream reader("map.txt");
	if (!reader)
		cerr << "Error opening file";
	else
	{
		for (int i = 0; i < TILE_Y; i++)
		{
			for (int j = 0; j < TILE_X; j ++)
			{
				reader >> map_tiles[i][j];
				reader.ignore();
			}
		}
	}
	
	//displaying map
	//when n = amount of tiles on x axis, create a new line for the next set 
	for (int i = 0; i < TILE_Y; i++)
	{
		for (int j = 0, n = 0; j < TILE_X; j++)
		{
			cout << map_tiles[i][j];
			n++;
			if (n == TILE_X)
				cout << "\n";
		}
	}

[Narue]

That's fine. For extra l33t points, you can also merge the input and output loops, or even get rid of the array altogether if that's the only place you use it.

[ichigo_cool]

void load_map(const char* filename)
{
	ifstream reader(filename);
	if (!reader)
		cerr << "Error opening file";
	else
	{
		for (int i = 0; i < TILE_Y; i++)
		{
			for (int j = 0, n = 0; j < TILE_X; j ++)
			{
				reader >> map_tiles[i][j];
				reader.ignore();
				cout << map_tiles[i][j];
				n++;
				if (n == TILE_X)
				cout << "\n";
			}
		}
	}
}

There's a merged function that can upload any txt file map... Hmm, how would I do it without the array? And I'm wondering about the necessity of it now, won't it be important in a map editor, or have I no idea?

[Narue]

Well, if you need the array for other purposes then it has to be there. But if all you're doing is reading from a file and displaying the contents, you can simply pull one record at a time and not bother storing past records:

for (int i = 0; i < TILE_Y; i++) {
    for (int j = 0; j < TILE_X; j++) {
        int tile;

        reader>> tile;
        reader.ignore();

        cout<< tile;
    }

    cout<<'\n';
}

[ichigo_cool]

great, i changed it to that as I don't believe I'll need the array too much.. Now I just need to include Allegro and change the cout to blit and blit the appropriate tiles according to the tile number, thanks so much or your help Narue!