int** malloc2d(int row, int col){   int** ret = (int**)malloc(sizeof(int*)*row);   int*      p=(int*)malloc(sizeof(int)*row*col);  if(ret&p){     for(i=0;i<row;i++){          ret[i]=p+i*col;    }  } else{     free(ret);     free(p);     ret=null;  }   return = ret;}