hi, i am loading in a binary file into a 2d vector. i have it working but don't understand how it works! lol here is the code....

int widthb[1];
int heightb[1];
int value1[1];

vector  > mapdata;

int LoadMapData()
{
	ifstream load;
	load.open("test.map", ios::binary);
	if (load.fail())
		return false;
	load.read((char*)widthb, 2);
	load.read((char*)heightb,2);
	mapxsize = *widthb;
	mapysize = *heightb;
	// this is to determine how big the map is.

	mapdata.resize(mapxsize);
		for (int i = 0; i < mapxsize; i++) 
			{
			mapdata.resize(mapysize);
			for (int j = 0; j < mapysize; j++) 
				{
				load.read((char*)value1, 1);
				
				mapdata[j] = *value1;
				}
			}
	load.close();

</pre> 

when i declare value1 as "int value1[1]" if i don't add the little array bit at the end it will not load the correct value when i use the load.read(), but i don't understand why. could someone please explain it to me???? or point me to a site that will help me understand it better? Also if anyone can explain why i have had to use pointers in this code, i can use them a little, but do not understand them yet!:mad:  lol

Thanks for any help u can give….

   </i>     </pre>  

Werdy666 <img src="smile.gif" width=15 height=15 align=middle>

<SPAN CLASS=editedby>[edited by - werdy666 &#111;n September 26, 2002 5:41:42 AM]</SPAN>    

You can change the variables back to regular integers if you use the & operator:

load.read((char*)&widthb, 2);

fstream (good) or fstream.h (bad) ?
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The reason that it works with the arrays, is that when you define an array (Eg. int widthb[1]), widthb is essentially a pointer to an intereger (the first in the array).

The fstream read operation must be given a pointer or reference to the memory it is to write to. So, in essence, you were unknowingly providing it with a pointer.

Probably a better way to do it is to either decalre
int *widthb;
load.read((char*)widthb, sizeof(int));

OR

int widthb;
load.read((char*)&widthb, sizeof(int));

Note that it is usually easier to use the ''sizeof(datatype)'' function to determine the number of bytes to read, rather than hardcoding a number there. You will find this espescially when you come to reading things like structs from files.