问为二维数组动态分配内存时出错

EN

   # include<iostream>
   # include<stdio.h>
   # include<conio.h>
   # include<stdlib.h>
   # define COLS 5
   using namespace std;

   typedef int Rowarray[COLS];
   int main()
   {
      Rowarray *rptr;
      int nrows=3;
      int row,col;
      rptr=(int**)malloc(nrows * COLS * sizeof(int)) ; // Error Line
      for(row=0;row<nrows;row++)
      { static int i=0;
        for(col=0;col <COLS;col++,i++)
        {
          rptr[row][col]=i;
        }
      }  
      for(row=0;row<nrows;row++)
      { 
        for(col=0;col <COLS;col++)
        {
          cout << "\n" << rptr[row][col];
        }
      }     
     getch();  
     return 0;
   }