Thread: changing the case of a string

what i'm trying to do is take the input from a file and change all the upper case letters to lower case and lower case letters to upper....now what i have so far does this but it doesn't keep the spaces from file it all just gets put on one line....

Code:

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

using namespace std;

void changecase(ifstream&, ofstream&);

int main()
{
  ifstream infile;
  ofstream outfile;
  infile.open("textforlab9");
  outfile.open("changedtextforlab9");

  changecase(infile, outfile);

  infile.close();
  outfile.close();

  return 0;
}

void changecase(ifstream& in, ofstream& out)
{
  char ch;
  while (!in.eof())
    {
      in >> ch;
      if (ch > 'A' && ch < 'Z')
        {
          ch = tolower(ch);
          out << ch;
        }
      if (ch > 'a' && ch < 'z')
        {
          ch = toupper(ch);
          out << ch;
        }
    }
}

ahh, but it's still outputting everything without spaces

That's because the streamextractors >> skip whitspace. you should use get().
Your while condition is wrong as well. Your way you would process the last character twice.
the preferred way woud be

Code:

  char ch;
  while ( in.get( ch ) ) {  // while no error reading from in ( eof is an error condition )
    ....

Kurt

You should use the get function, not getline. The get function as shown reads in each and every character, including whitespace. ZuK's example should be all you need to get going.

You don't really want the getline function either, because it discards newlines. You could use it if you wanted, but that would take extra code to read in the line and then loop through each character in the string.

One other option is to keep your original code but to use the noskipws manipulator to stop operator>> from skipping whitespace. I think get() is simpler, though.

ahh daved thanks for the noskipws advice it's working perfectly now

Originally Posted by ammochck21

kurt: with the way you have the while statement it did stop processing the last character twice...but now it doesn't process the 1st character

Code:

void changecase(ifstream& in, ofstream& out)
{
  char ch;
  while (in.get(ch))
    {
//      in >> ch;          // you already read the char in the while condition.
                           //  must be removed

Kurt