C++ Cookbook

4.20. Justify a Text File

Problem

You want to right- or left-justify text.

Solution

Use streams and the standard stream formatting flags right and left that are part of ios_base, defined in <ios>. Example 4-29 shows how they work.

Example 4-29. Justify text

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>

using namespace std;

int main(int argc, char** argv) {

   if (argc < 3)
      return(EXIT_FAILURE);

   ifstream in(argv[1]);
   ofstream out(argv[2]);

   int w = 72;
   if (argc == 4)
      w = atoi(argv[3]);

   string tmp;
   out.setf(ios_base::right);   // Tell the stream to
                                // right-justify
   while (!in.eof()) {
      out.width(w);                  // Reset width after
      getline(in, tmp, '\n');        // each write
      out << tmp << '\n';
   }
   out.close();
}

This example takes three arguments: an input file, an output file, and the width to right-justify to. You can use an input file like this:

With automatic download of Microsoft's (Nasdaq:
MSFT) enormous SP2 security patch to the Windows
XP operating system set to begin, the industry
still waits to understand its ramifications. Home
users that have their preferences set to receive
operating-system updates as they are made
available by Microsoft may be surprised to learn
that some of the software they already run on
their systems could be disabled by SP2 or may run
very differently.

and make it look like this:

 With automatic download of Microsoft's (Nasdaq: MSFT) enormous SP2 security patch to the Windows XP operating system set to begin, the industry still waits to understand ...