DEKEY.H

#ifndef DEKEY_H    // To make sure you don't declare the function more than once by including the header multiple times.
#define DEKEY_H

#include<iostream>
#include<fstream>
#include<cctype>

using namespace std;


void DeKey(char file1[20],char file2[20])
{
    ifstream infile;
    ofstream outfile;

    char d[100];
    cout<<"\nEnter the keyword\n";
    cin >> d;

    infile.open (file1);    //opens the file to be encrypted
    outfile.open (file2); //opens the output file

    char c;

    while (!infile.eof()) { //while not the end of the file
       
        infile >> c;

            for(int j = 0; d[j] != '\0'; j++) {
                
                if ( (c - 3) == d[j]) {
                    c -= 3;
                    break;
                }

            }

            if(c < 'a'){
			
                c += 26;
			}

            outfile << c;

    }

    outfile << "\n\n";  //aesthetic purposes
    
    infile.close();	 //closes the original file
    outfile.close();	//closes the file encryption

}

#endif