~cpp
#include <fstream>
#include <string>
#include <iostream>
using namespace std;
int main()
{
ifstream fin("source.txt"); // fin input.txt
ofstream fout("output.txt"); // fout output.txt
char array[100];
int counter = 0;
for(int i=0; !fin.eof(); i++)
{
array[i]=fin.get(); // cin 화 , fin 파 .
counter++;
}
int key;
cout<<"호화 키 하 = >" ;
cin >> key;
//호화
for(i=0; i< counter-1; i++)
{
array[i] += key;
}
for(i=0; i<counter-1; i++)
{
cout<<array[i];
fout<<array[i];
}
cout<<endl;
//해
for(i=0; i<counter-1; i++)
{
array[i] -= key;
}
for(i=0; i<counter-1;i++)
{
cout<<array[i];
}
cout<<endl;
return 0;
}