Teksto šifravimas [C++]

#include <iostream>
#include <fstream>
 
using namespace std;
 
int main(){
 
 
	cout << "Kodavimas atliekamas, panaudojant XOR metoda\n \n";
 
	//-------------Meniu1--------------------
 
	cout << endl <<"Ka dariti?\n";
	cout << "1. txt --> Code\n";
	cout << "2. Code --> txt\n";
 
	int in;
	cin >> in;
 
	string a,b;
 
	if(in==1){
		a="input.txt";
		b="output.txt";
	}
	else {
		a="output.txt";
		b="output2.txt";
	}
 
 
	ifstream infile;
	ofstream outfile;
 
 
	infile.open (a.c_str());
	outfile.open (b.c_str());
 
	if (!infile)
		cout << "Failo nera" << endl;
 
	string s;
    char temp;
 
    infile.unsetf(ios::skipws);
    while(infile >> temp)
        s += temp;	
 
	unsigned long key=0;
	string pass;
 
	cout << "Iveskite slaptazodi ir isimikite ji\n";
	cin >> pass;
 
	for (int i=0; i<=pass.size(); i++) 			
		key=key+pass[i];
 
 
	if(in==1){
 
		for (int i = 0; i < s.size(); i++)
			s[i] = s[i] ^ key;
		outfile << s ;
	}
 
	if(in==2){
		for (int i = 0; i < s.size(); i++)
			s[i] = s[i] ^ key;
		outfile << s ;
	}
 
	outfile.close();
 
 
    system("PAUSE");
    return EXIT_SUCCESS;
}

#include <iostream>
#include <fstream>
 
using namespace std;
 
inline bool odd(long value){
 
	return (value & 1) == 1;
}
 
int main(){
 
	cout << "1. Sifruoti\n";
	cout << "2. Issifruoti\n";
 
	int pasirinkimas;
	cin >> pasirinkimas;
 
 
	if (pasirinkimas == 1){
 
		ifstream infile("infile.txt");
		ofstream outfile("outfile.txt");
 
		if (!infile)
			cout << "Failo nera" << endl;
		string s;
		char temp;
 
		infile.unsetf(ios::skipws);
		while(infile >> temp)
			s += temp;
 
		for (int i=0; i<s.size(); i++) {
			if (odd(i)==false){
				temp=(char) s[i]+2;
				outfile << temp;
			}
			else{
				temp=(char) s[i]-2;
				outfile << temp;
			}
		}
 
		outfile.close();
 
	}
 
	else if (pasirinkimas==2){
 
		ifstream infile("outfile.txt");
		ofstream outfile("infile_new.txt");
 
		if (!infile)
			cout << "Failo nera" << endl;
 
		string s;
		char temp;
 
		infile.unsetf(ios::skipws);
		while(infile >> temp)
			s += temp;
 
		for (int i=0; i<s.size(); i++) {
			if (odd(i)==false){
				temp=(char) s[i]-2;
				outfile << temp;
			}
			else{
				temp=(char) s[i]+2;
				outfile << temp;
			}
		}
 
		outfile.close();
	}
 
	system("PAUSE");
	return 0;
}