problem with map file

Author

134

February 17, 2005 02:30 PM

Hellu there! This is map.map file: 1111111111111 2222222222222 1111111111111 and so on, where 1=WATER, 2=GRASS and so on... some code:


	FILE *f;
	f=fopen("maps/desert.map","r");
  	if (f==NULL) perror ("Error opening file desert.map");
  	else
  	{
    		fseek (f, 0, SEEK_END);
    		size=ftell (f);
		bytecount = size;  	
		fseek (f, 0, SEEK_SET);
	}

	int rows, columns;
	int temp;
	for(rows=0; rows<25; rows++)
	{
		for(columns=0; columns<34; columns++)
		{
			temp = fgetc(f)-48;
			map[rows][columns] = temp;
			printf("%i", map[rows][columns]);
		}
		printf("\n");
		temp = fgetc(f)-48;	
	}

So now to my problem. The "rows<25" and "columns<34", i want them to be read directly out of the file so its automatic so if this is my map file: 2222222222 2222222222 2222222222 2222222222 2222222222 (COLUMNS: 10, ROWS:5) the "25" in the for and the "34" in the for loop, shall be "10" and "5" Get it? Otherwise for example, if it was "for(columns=0; columns<20"; columns++)" The map would look like this: 22222222222222222222 22222222222222222222 2222222222 Get it? thanks.

peb

Author

134

February 17, 2005 02:36 PM

OHHH SHIT! im so sorry for double post... i swear it wont happen again

evillive2

779

February 17, 2005 05:13 PM

There are many ways to do this but a couple of ways to do this might be:

Most common is to just store the array size at the beginning of the map file:

5 4
11111
22222
11111
12121

Another way is to count the number of characters in the first line until the newline to get the number of collumns and then count the total number of newlines to get the number of rows.

Hope that helps

Evillive2

peb

Author

134

February 18, 2005 05:58 AM

Yeah okay, can you give me some code for it?

Zeophlite

144

February 19, 2005 02:41 AM

Using evillive2's map:
5 4
11111
22222
11111
12121

char buffer[255];
fgets(buffer, 255, f);
int ncolumns, nrows;
sscanf(buffer, "%d %d", &rows, &ncolumns);

evillive2

779

February 21, 2005 08:45 PM

Quote:
Zeophlite:
char buffer[255];
fgets(buffer, 255, f);
int ncolumns, nrows;
sscanf(buffer, "%d %d", &rows, &ncolumns);

There are many tutorials and source code examples on the web for C style file I/O routines. Here is a modified one for reading in a number from a file:

// text mode file I/O. Read a single integer from a file.// Building on this function floating point numbers are simple to add.int fread_integer( FILE *fp ){    int number;    bool sign;    char c;    // skip leading spaces    do    {	c = getc( fp );    }    while ( isspace(c) );    number = 0;    // check sign    sign   = FALSE;    if ( c == '+' )    {	c = getc( fp );    }    else if ( c == '-' )    {	sign = TRUE;	c = getc( fp );    }    // check if it is a digit    if ( !isdigit(c) )    {	// options: try to continue or exit	// this is a good reason to have some error logging	// system	return 0;    }    // read in the digits    while ( isdigit(c) )    {	// this works for base 10 numbers	// and isnt' that much different for 	// numbers after a decimal point	number = number * 10 + c - '0';	c      = getc( fp );    }    // modify the sign of the number    if ( sign )	number = 0 - number;    // again, this is where error logging comes in handy    // also, this is where you can expand upon reading in digits    // AFTER a decimal point.    if ( c != ' ' )	ungetc( c, fp );    // the payoff    return number;}

I don't make any claims that this is the best way to do things, just one that works and is very easy to use. If you leave a space between all the numbers it would look somethingl ike this:

FILE *fp;int width, height;int row, col;fp = fopen( "map.map", "r" );width = fread_number(fp);height = fread_number(fp);for ( row = 0; row < height; row++ )    for ( col = 0; col < width; col++ )        map[col][row] = fread_number(fp);

In all fairness even though text files are great for flexibility and readablility, once you get into larger maps the text files can become rather huge rather quickly. Since you will probably create an editor later on, the readability won't be as much of an issue but for some people the download size will be. Then, binary files will provide you with a few things, smaller file size, faster parsing (in many cases anyway, this one in particular), and hiding the data you might not want changed from every day average joe user.

Hope that helped.

p.s. I didn't develop that code snippet above. I am not sure who contributed the original but a similar version can be found in almost any Merc Diku MUD derivitive which are available for download and use from many places such as ftp.game.org.

Evillive2

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