#include<iostream>
#include<fstream>
#include<cstdlib>
#include<string>
using namespace std;

string replace_all(ifstream infile,string from,string to)
{
 string str;
 infile>>str;
 cout<<"The basic string: "<<str<<endl;
 //replace:
 for(string::size_type pos(0);pos!=string::npos;pos+=to.length())
 {
  if((pos=str.find(from,pos))!=string::npos)
   str.replace(pos,from.length(),to);
  else
   break;
 }

 return str;
}

int main()
{
 string s,f,t;
 ofstream outfile("IOreplace.dat",ios::out);
 if(!outfile)
 {
  cerr<<"open error!"<<endl;
  exit(1);
 }
 cin>>s;
 outfile<<s;
 outfile.close();

 //infile and replace
 ifstream infile("IOreplace.dat",ios::in);
 if(!infile)
 {
  cerr<<"open error!"<<endl;
  exit(1);
 }
 cin>>f>>t;
 cout<<"After replace: "<<replace_all(infile,f,t);

 infile.close();

 return 0;
}

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