Allocating memory...

**PsychoBrat** · 01-17-2003

Hi all!
I have a problem. I need to be able to modify the size of a multidimensional array, and I made a li'l test doing it with an array that only has one dimension successfully... (i'm using "php" tags rather than code tags cuz well.... it just looks cooler!)

PHP Code:


int max = 8;           // initial size of aray

int* a = new int[max];  // allocated on heap



for (int j=0; j<max; j++)

{

    a[j]=j;

}



max = max / 2;            // halve the previous size

int* temp = new int[max]; // create new bigger array.

for (int i=0; i<max; i++)

{

    temp[i] = a[i];       // copy values to new array.

}

delete [] a;              // free old array memory.

a = temp;                 // now a points to new array.

    

for (j=0; j<max; j++)

{

    printf("%d\n", a[j]);

}



printf("Done - hit a key you ass!");

getch();

The problem is, i've heard some scary **** - that all dimensions other than the first must be static values even when allocating memory in this way. Can anyone help me out with a good method of dynamically creating a 2 dimensional array?

Thanks in advance ppl!

**rmullen3** · 01-17-2003

I forget who originally wrote this code...

Code:

#include <iostream>
using namespace std;

int main (void) {

  // 2-dimensional dynamic matrix 
  int **dynamicMatrix = NULL;

  int numRows    = 0;
  int numColumns = 0;

  int row    = 0;
  int column = 0;

  cout << "Enter number of rows: ";
  cin >> numRows;

  cout << "Enter number of columns: ";
  cin >> numColumns;

  dynamicMatrix = new int*[ numRows ];

  for( row = 0; row < numRows; row++ ) {

    dynamicMatrix[ row ] = new int[ numColumns ];
  }

  // set it all to 5
  for( row = 0; row < numRows; row++ ) {

    for( column = 0; column < numColumns; column++ ) {

      dynamicMatrix[ row ][ column ] = 5;
    }
  }

  return 0;
}

**PsychoBrat** · 01-17-2003

oooooooooooooh!

Thankyou soooo much!

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