Turbo Toolbox/Turbo_Toolbox.iso/dtx9202/borhot/cincoutd.cpp

C/C++ Source or Header | 1992-01-06 | 5KB | 200 lines

/* ------------------------------------------------------ */
/*                   CINCOUTD.CPP                         */
/*              Redirecting CIN or COUT                   */
/*            (c) 1990 Borland International              */
/*                 All rights reserved.                   */
/* ------------------------------------------------------ */
/*  veröffentlicht in: DOS toolbox 2'92                   */
/* ------------------------------------------------------ */

/*
  In the following program, the input with CIN can be
  redirected to gather the data from a file, or the output
  with COUT can be redirected to a file or stdprn depending
  on the program's command line arguments.
*/

#include <fstream.h>
#include <iostream.h>
#include <io.h>
#include <fcntl.h>
#include <process.h>
#include <string.h>
#include <sys\stat.h>

#define  PRNHANDLE  4
#define  ARRAYSIZE  80

void OutputUsage(void);
int  OpenOutFile(char *);
int  OpenInFile(char *);

int main(int argc, char *argv[])
{
  char      io = 0;       // Keeps track if CIN or COUT
                          // redirection
  filebuf   *fBuf;        // Filebuf created with stdprn
                          // filehandle
  streambuf *oldBuf;      // Used to hold the old streambuf
                          // while CIN or COUT is being
                          // redirected
  unsigned  fhndl = -1;   // File handle of redirected file

  char      a[ARRAYSIZE + 1];   // Used for the sample I/O

  if (argc != 2) {
    switch(argv[1][0]) {        // Check the second command
                                // argument

    // Redirect CIN to gather from file specified at
    // command line
      case 'I':
      case 'i':

    // Capture CIN's current streambuf before it is
    // reassigned
        oldBuf = cin.rdbuf();
        io     = 'i';

    // Opens file specified at command line and redirects
    // CIN to extract from it
        fhndl = OpenInFile(argv[2]);
        break;

    // Redirect COUT to output to file specified
    // at the command line
      case 'O':
      case 'o':

    // Capture COUT's streambuf before new
    // streambuf * is assigned.
        oldBuf = cout.rdbuf();
        io     = 'o';

    // Opens file specified at command line and
    // redirects output via COUT to file
        fhndl = OpenOutFile( argv[2] );
        break;

    // Redirect COUT to stdprn
      case 'P':
      case 'p':

    // Create a new filebuf with the file handle to stdprn
        fBuf = new filebuf(PRNHANDLE);

    // Use overloaded assignment operator to assign
    // new filebuf to COUT
        cout = fBuf;
        break;
      default:

    // If no command line arguments specified, use
    // default settings for CIN and COUT
        if (argc == 1) {
          break;
        }
    // Output command line usage if 2nd command
    // line argument incorrect
        OutputUsage();
      }
    }

    // NOW NORMAL USE OF CIN AND COUT WILL HONOR ANY
    // REDIRECTION DONE ABOVE

    // Simple demonstration of CIN inserting characters
    // into array 'a'
    cin.getline(a, ARRAYSIZE);

    // Check to make sure the previous function call did
    // not produce errors
    if (cin.fail()) {
      return 1;
    }

    // Simple demonstration of COUT outputting contents
    // of 'a' to output stream
    cout << a << endl;

    // If a file was opened for redirection, close that file
    if (fhndl != -1) {
      close(fhndl);

    // Reassign the old streambuf * to either CIN or COUT
      if (io == 'i') {
        cin = oldBuf;
      }
      else if (io == 'o') {
        cout = oldBuf;
      }
    // NOW CIN AND COUT HAVE BEEN SET TO ORIGINAL STATE
    }
  return 0;
}

int OpenOutFile(char *filename) {
  filebuf *tmpFBuf;
  int     fhndl;

  fhndl = open(filename, O_CREAT|O_TEXT|O_RDWR,
                         S_IREAD|S_IWRITE);
  if (fhndl == -1) {
    cout << "Error opening file " << filename
         << ", program terminated.";
    cout << endl;
    exit(1);
  }

  // Create new filebuf with file handle of file specified
  // at command line
  tmpFBuf = new filebuf(fhndl);

  // Use overloaded assignment operator to assign new
  // filebuf to COUT
  cout = tmpFBuf;
  return fhndl;
}

int OpenInFile(char *filename) {
  filebuf *tmpFBuf;
  int     fhndl;

  fhndl = open(filename, O_CREAT|O_TEXT|O_RDONLY,
                         S_IREAD|S_IWRITE );
  if (fhndl == -1) {
    cout << "Error opening file " << filename
         << ", program terminated.";
    cout << endl;
    exit(1);
  }

  // Create new filebuf with file handle of file specified
  // at command line
  tmpFBuf = new filebuf(fhndl);

  // Use overloaded assignment operator to assign new
  // filebuf to CIN
  cin = tmpFBuf;
  return fhndl;
}

void OutputUsage( void ) {
  cout << endl
       << "Usage: <exe filename> [I, O, ?, h] <filename>"
       << endl;
  cout <<
  "I - cin will be redirected to input from  <filename>."
       << endl;
  cout <<
  "O - cout will be redirected to output to <filename>."
       << endl;
  cout <<
  "P - cout will be redirected to output to stdprn."
       << endl;
  cout << "? or h - Outputs this screen." << endl;
}
/* ------------------------------------------------------ */
/*                Ende von CINCOUTD.CPP                   */