C++

Forum

 
Dynamic 2d array access violation?

LordSimpson (2)
Hi im trying to get some code to work and i keep getting 

First-chance exception at 0x00f32d34 in prog.exe: 0xC0000005: Access violation reading location 0x333f8630.
Unhandled exception at 0x00f32d34 in prog.exe: 0xC0000005: Access violation reading location 0x333f8630.


What i want is a 2d dynamic array/matrix of size [b by b].

This array is used to check if an event will happen, I require it first to be filled with 0's then filled with ones along the diagonal e.g.

1000
0100
0010
0001

This array/matrix has to be used and cleaned meny times so im trying to make a function that would do this so i dont have to have the same lines over and over. so far ive got this.

The function that should input the diagonal

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
 
inline int** matrixrefresh(int**& a, int& b)
{
	int i;
	// declaration
	int ** c;

	// allocation
	c = new int*[b];
	for(int i = 0; i < b; i++)
		c[i] = new int[b];

	// initialization
	for(int j = 0; j < b; j++)
		for(int i = 0; i < b; i++)
			c[i][j] = 0;


	while(i < b)
	{
	    c[i][i] = 1;
	    i++;
	}
	a = c;
	return a;
	}


Then Mid way through int main the matrix I'm going to use is made and initialised

1
2
3
4
5
6
7
8
9
10
11
12
 
// declaration
int ** checkingmatrix;

// allocation
checkingmatrix = new int*[b];
for(int i = 0; i < b; i++)
	checkingmatrix[i] = new int[b];

// initialization
for(int j = 0; j < b; j++)
	for(int i = 0; i < b; i++)
		checkingmatrix[i][j] = 0;


Then i call the function to input the diagonal
matrixrefresh(checkingmatrix,b);

Then finaly leter on inside a few while loops its used for checking

1
2
3
4
 
if (checkingmatrix[a][b] = 0)
{
  stuff
}


It compiles and works fine untill this part of the function. [the c[i][i] line to be exact]

1
2
3
4
5
 
	while(i < b)
	{
	    c[i][i] = 1;
	    i++;
	}


Any help would be greatly appreciated. Also just to note I don't know to much about c++ most of this code has been grabbed of various forum posts around the net and cobbled together.
Last edited on
helios (17574)
i is uninitialized at the beginning of the loop.
LordSimpson (2)
how the hell...i had that problem an hour ago, fixed it and it did nothing, did it again now and it seams to work fine....
Topic archived. No new replies allowed.