I'm trying to use the command line prompt to perform four operations. Encrypt a .txt file, decrypt a .txt file, output the first five lines on the screen, output the last five lines on the screen. I can encrypt and decrypt the file but I can't get the first five lines to print. Any help?
Code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int htlen=5;
const int ascLEn=256;
const int ecryptCode=10;
void print_usage()
{
      cout<<"Usage"<<endl;
      cout<<"      lab12 -e file1 file2  Encrypt file1 and write cyphertext to file2"<<endl;
      cout<<"      lab12 -d file1 file2  Decrypt file1 and write paintext to file 2"<<endl;
      exit(1);
}
int main(int argc, char* argv[])
{
      if (argc != 4)
            print_usage();
            if (strcmp(argv[1], "-e") !=0&&strcmp(argv[1], "-d")!=0)
                  print_usage();
      ifstream inData;
      ofstream outData;
      inData.open(argv[2]);
      outData.open(argv[3]);
      if (inData.fail()||outData.fail())
      {
            cout<<"File open error!"<<endl;
            return 1;
      }
      string s;
      if (strcmp(argv[1], "-e")==0)
      {
            while (!inData.eof())
            {
                  getline(inData, s);
                  for (int i=0;i<s.length();i++)
                        s[i]=char(s[i] + ecryptCode)%ascLEn;
                  outData<<s;
                  if (!inData.eof())
                        outData<<endl;
            }
      }
      else
      {
            while (!inData.eof())
            {
                  getline(inData, s);
                        for (int i=0;i<s.length();i++)
                              s[i]=char(s[i]+ascLEn-ecryptCode)%ascLEn;
                  outData<<s;
                  if (!inData.eof())
                        outData<<endl;
            }
      }
      inData.close();
      outData.close();
      return 0;
      system("pause");
}