Dynamic Arrays

[Nova]

Hey everyone,

I am searching for a way to dynamically change the size of an array during runtime.
I will create an example to explain what I want to do:

Let's say we have a class (partly pseudo code)

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class MyClass {
private:
  <array of integer> walkmap
  void CreateMap(int map);
};

walkmap is supposed to be a 2d array of integers that holds diffrent values for different map types [0=not walkable,1=walkable], so the AI could access this walkmap during its pathfinding algorythms

Of course different maps have different walking abilities, therefore I have created the CreateMap() function


My problem is that different maps, too have different sizes:

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void MyClass::CreateMap(int map) {
	switch(map) {
		case 1:
		{
			walkmap[0] = 0 0 0 1 1 1 0 0 0;
			walkmap[1] = 0 0 1 1 1 0 0 1 1;
			walkmap[2] = 0 0 1 1 0 0 1 1 0;
			walkmap[3] = 0 0 0 1 1 1 1 0 0;
		}
		case 2:
		{
			walkmap[0] = 0 0 0 1 1 1 1 1 1 1 1 1 1 1;
			walkmap[1] = 1 1 1 1 1 1 0 0 0 0 0 0 0 0;
		}
	}
}

So how can I make the different walkmaps but still use the walkmap variable?

thnx in advance
-Nova

[Xico]

Using vectors as container instead of arrays?
here info about vector and other container classes: http://www.roguewave.com/support/docs/s ... f/2-7.html
hope it help
regards

[bitplane]

you could use irrlicht's inbuilt arrays, they handle their own memory allocation but I think they are limited to one dimension-

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core::array<int> map;
// then...
if ( map.size() < width * height) 
  map.set_used(width * height);
map[x+(y*width)] = whatever;

i found that irrlicht's arrays are slow when you heavily use [] operators inside loops, so use the array class for its memory management but read and write the data manually using good old c pointers. eg-

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int *arraydata;
core::array<int> map;

map.set_used(100);  // grow the array
arraydata = map.pointer(); // get memory location

// 
for (int i = 0; i<100; i++) 
{
    // "map[i]" means call core::array's [] function to get the int
    // "arraydata[i]" means "an integer at location arraydata+(sizeof(int)*i)"
    arraydata [i] = somecalculation(i);
}

[Masdus]

Its to dynamically resize c++ arrays, i remember doing in back in 2nd year Uni. Problem is i can't remeber how its done. I'm sure a google search will turn up some example code,

[bearSoft]

u need to allocate heap memory using the 'new' operaor
eg
int *vek = new int[n][m];

when not needed anymore remember to free the heap
delete [] vek;

it is also posible to build a template class so that different types can be stored in the same vektor, however big isues vith the operators emerges