cipherbasic.cpp

#include<iostream>
#include<fstream>
using namespace std;
int encryption();
int decryption();

int main()
{
    encryption();
    decryption();
    return 0;
}

int encryption()
{
    ifstream iFile;
    ofstream oFile;
    int key = 3;
    char line[200] = "";
    char cipher[200] = "";
    iFile.open("plaintext.txt", ios_base::in);
    oFile.open("cipher.txt", ios_base::out);

    if (!iFile.is_open() || !oFile.is_open()) //! - logical NOT operator
    {
        cout << "Input FileIO error!, exiting...." << endl;
        exit(0);
    }
    while (iFile.getline(line, 200))
    {
        puts(line);
        int i = 0;
        for (i = 0;  i < 200; i++)
        {
            cipher[i] = '\0';
        }
        for (i = 0; line[i] != '\0' && i < 200; i++)
        {
            cipher[i] = line[i] + key;
        }
        cipher[i] = '\0';
        oFile << cipher << endl;
        puts(cipher);
        for (int j = 0; j < 200; j++)
        {
            line[j] = '\0';
        }
    }
    iFile.close();
    oFile.close();
    return 0;
}

int decryption()
{
    ifstream iFile;
    ofstream oFile;
    int key = 3;
    char line[200] = "";
    char plain[200] = "";
    iFile.open("cipher.txt", ios_base::in);
    oFile.open("original.txt", ios_base::out);
    if (!iFile.is_open() || !oFile.is_open())
    {
        cout << "Input FileIO error!, exiting...." << endl;
        exit(0);
    }
    while (iFile.getline(line, 200))
    {
        puts(line);
        for (int i = 0; i < 200; i++)
        {
            plain[i] = '\0';
        }
        for (int i = 0; line[i] != '\0' && i < 200; i++)
        {
            plain[i] = line[i] - key;
        }
        oFile << plain << endl;
        puts(plain);
    }
    iFile.close();
    oFile.close();
    return 0;
}