C - C++ Files - File merge

#include<iostream.h>
#include<conio.h>
#include<fstream.h>
#include<stdio.h>
 
void main() 
{
  clrscr();
  char ch,st[100],cha,ts[100];
  ofstream o("r.txt");
  cout<<"\n Enter the contents of file1:";
 
  do 
  {
    ch=cin.get(); fflush(stdin);
    o.put(ch); 
  } while(ch!='.');
 
  o.close();
  ofstream t("u.txt");
  cout<<"\n Enter the contents fo file2:";
 
  do 
  {
    cha=cin.get();
    fflush(stdin);
    t.put(cha);
  } while(cha!='.');
 
  t.close();
  ifstream i,j;
 
  i.open("r.txt");
  j.open("u.txt");
 
  fstream k; 
  k.open("m.txt",ios::app);
 
  while(!i.eof()) 
  {
    fflush(stdin);
    i.read((char*)&st,sizeof(st));
    fflush(stdin);
    k.clear();
    k.write((char*)&st,sizeof(st));
    cout<<st;
  }
 
  while(!j.eof())
  {
    fflush(stdin);
    j.read((char*)&ts,sizeof(ts));
    fflush(stdin);
    k.clear();
    k.write((char*)&ts,sizeof(ts));
    cout<<ts;
  }
 
  getch();
}