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From: gregs@hpmtlx.HP.COM ($Greg_Stander)
Newsgroups: comp.lang.c++
Subject: Re: new on two dimension array
Message-ID: <5370002@hpmtlx.HP.COM>
Date: 26 Oct 90 16:36:33 GMT
References: <1990Oct17.153438.12299@swbatl.sbc.com>
Organization: HP Manufacturing Test Division - Loveland, CO
Lines: 36

> Novice question: how do you use new to allocate space for a two
> dimension array?
> 
> char **matrix = new ??????;

Of course if dimensions are constants, this works and is usually easier.

#include <stream.h>
#include <stdio.h>

const int XMAX =   3;
const int YMAX =  20;
typedef char array_type[XMAX][YMAX];

main()
{
  array_type &myarray = *(array_type *)new char[XMAX * YMAX];

  // Init to some values
  for(int row=0; row<XMAX; row++)
    for(int col=0; col<YMAX; col++)
      myarray[row][col] = 'z';
  for(row=0; row<XMAX; row++)
    sprintf(myarray[row], "This is row %d", row);

  // Show as array
  for(row=0; row<XMAX; row++)
      cout << "myarray[" << row << "] = " << myarray[row] << "\n";
  
  // Show as individiual characters
  char *show = (char *)myarray;
  for(int index = 0; index<XMAX*YMAX; index++)
    cout << show[index] << (((index+1)%YMAX)?"":"\n");
}

Greg Stander