//********************************************************
//func seekp():direct access to file using writing pointer
//ostream &seekp(off-type offset, seekdir origine);
//********************************************************

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

//-------------------------------------------------------
int showFileContent(){
	char ch;
	ifstream testl("testchar",ios::in|ios::binary);	
	if(!testl){
		cout<<"Error opening file in testl\n";
		return 1;
	}
	while(!testl.eof()){
		testl.get(ch);
		cout<<ch;
	}	
	cout<<endl;
	testl.close();
	return 0;
}

//-------------------------------------------------------
int editFileContent(int val,char *speech){
/*stream must be opened with fstream to work well with seekp/seekg*/
	fstream out("testchar",ios::out|ios::in|ios::binary);
	if(!out){
		cout<<"Error opening file in out\n";
		return 1;
	}
	val=val-1;
	out.seekp(val,ios::beg);
	
	out.write(speech,sizeof(speech));

	out.close();
	return 0;		
}
//=======================================================
int main(){
	int pos;
	char speech[100];
	cout<<endl<<endl;
	showFileContent();
	cout<<"Insert position from begins to insert speech: ";	
	cin>>pos;
	cout<<"Insert speech: ";
	cin>>speech;	
	editFileContent(pos,speech);
	showFileContent();
	return 0;
}


//output file for position 33 and speech Stella
/*             first
012345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567899

Insert position from begins to insert speech: 33
Insert speech: Stella

                after           (..)
01234567890123456789012345678901Stel678901234567890
12345678901234567890123456789012345678901234567899*/