[Dev-C++] RES: function for allocate memory for 2D vectors

My way of understand your recommendations
did result in this:

//////code///////////
#include <stdio.h>
#include <stdlib.h>

int **Alocate2DVect(int lin, int col)
{
   int i, **vect;

   vect = (int **) malloc(lin*sizeof(int));
   if(!vect) return(NULL);
   for(i=0; i<col; i++){
      vect[i] = (int *) malloc(col*sizeof(int));
      if(!vect[i]) return(NULL);
   }
   return(vect);
}

int main()
{
   int **vector2D;
   int i, j, lin=3, col=4;

   vector2D = Alocate2DVect(lin, col);
   if(!vector2D) exit(EXIT_FAILURE);

   for(i=0; i<lin; i++)
      for(j=0; j<col; j++)
         vector2D[i][j] = i + j;

   for(i=0; i<lin; i++){
      for(j=0; j<col; j++){
         printf("%d\t", vector2D[i][j]);
      }
      printf("\n");
   }

   for(j=0; j<col; j++)
      free(vector2D[col]);
   free(vector2D);

   system("PAUSE");
   return 0;
}

///////// end of code ////////

Is it ok?

Thanks!
André


-----Mensagem original-----
De: Per Westermark [mailto:pw...@ia...]
Enviada em: domingo, 11 de novembro de 2007 04:27
Para: André Macário Barros
Cc: dev...@li...
Assunto: Re: [Dev-C++] function for allocate memory for 2D vectors


First of all - your code would be a bit simpler (you would loose one
indirection) if you modify Allocate2DVect (two l in allocate) to return
the pointer instead of taking it as a parameter.

Second: your test if (!vect) does not check the result of the allocation,
but if you sent a pointer in to the function.

Third: You normally don't need to release memory before ending a program,
but if you do, then your code is incorrect. You need to release all
columns before releasing the row vector.

/pwm

On Sun, 11 Nov 2007, André Macário Barros wrote:

> Dear Users,
>
>    Could you confirm if this function is
> correct?
>    The reason of my question is: inspecting
> the address of *vect in line x in the function
> is different of line y. I was expecting equal
> addresses, wasn´t?
>
> ////////// code /////////////////////////
>
> int Alocate2DVect(int ***vect, int lin, int col)
> {
>    int i, *pont;
>
>    *vect = (int **) malloc(lin*sizeof(int)); // line x
>    if(!vect) return(0);
>    for(i=0; i<col; i++) *(*vect + i) = (int *) malloc(col*sizeof(int));
>    if(!vect) return(0); // line y
>    return(1);
> }
>
	> int main()
> {
>    int **vector2D;
>    int i, j, lin=3, col=4;
>
>    if(!Alocate2DVect(&vector2D, lin, col)) exit(1);
>
>    for(i=0; i<lin; i++)
>       for(j=0; j<col; j++)
>          vector2D[i][j] = i + j;
>
>    for(i=0; i<lin; i++){
>       for(j=0; j<col; j++){
>          printf("%d\t", vector2D[i][j]);
>       }
>       printf("\n");
>    }
>
>    free(vector2D);
>    system("PAUSE");
>    return 0;
> }
> //////////// end of code /////////
>
> Regards
> Andre
>
>
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> 15:47
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Checked by AVG Free Edition.
Version: 7.5.503 / Virus Database: 269.15.28/1123 - Release Date: 10/11/2007
15:47