function/variable isolation out of scope

This is a simple problem I try to solve.  I forgot how to do that.  That will probably take me a while to figure out.  I may have made a mistake in memory allocation (malloc), but I don't see it.

The problem is, inside the function, the output variable gives good result (0 and 1), and outside the function, the output variable give wrong result (print memory location instead of 1 and 0).

Here is the code, you can try to compile it and see the problem

thanks

#include <iostream.h>
#include <math.h>
#include <stdlib.h>
#include <conio.h>


void deci2bin(int d, int size, int *b)
      {
   int i;

   for(i = 0; i < size; i++)
         {
      b[i] = 0;
      }
   b[size - 1] = d & 0x01;

    for (i = size - 2; i >= 0; i--)
          {
      d = d >> 1;
      b[i] = d & 0x01;
          }
      }


void gen01dat( long data_len, int *out_array)
      {
   long t,j;
   int y1[100];
   int b[100];
   int y2[100][8];
   int y3[800];
   int y4[800];
   out_array = (int*)malloc(800*sizeof(int));


    for (t = 0; t < data_len; t++)
          {
      out_array[t] = ceil(127*sin(0.5*t));
      }

        for (t =0;t<100;t++)
         {
      deci2bin(out_array[t],8,b);
         for (j=0;j<8;j++)
            {
         y2[t][j] = b[j];
         }
      }

   for (t=0;t<100;t++)
         {
      for (j=0;j<8;j++)
            {
         y3[8*t + j] = y2[t][j];
         }
      }

   for (t=0;t<800;t++)
         {
      out_array[t] = y3[t];
      }

   for (t=0;t<800;t++)
         {
      y4[t] = 1;
      if (out_array[t] < 0)
            {
         out_array[t] = -out_array[t];
         y4[t] = -1;
         }
      y4[t] = out_array[t] * y4[t];
      }

   for (t=0;t<800;t++)
         {
     out_array[t] = y4[t];
      }

   for(int i=0;i<20;i++)
         {
      cout<<out_array[i];
      }
      cout<<endl;

   free(out_array);
   }

void main()
      {
   long n;
   int out[20];

   gen01dat(n,out);
   for (int i=0;i<20;i++)
         {
      cout<<out[i];
      cout<<endl;
      }
   getch();
   }