Q:

C++ ifstream ofstream implementation?

I have been writing this Pig Latin program to convert english to pig latin, and I have been having issues implementing the read in file and then subsequently outputing it to another txt file.
This is what I have so far, but it wont compile because of 
outputFile << pigLatin(englishWord) << ' ';

Here is the source code. Any suggestion to get it working? Thanks
void pigLatin(string englishWord)
{
string piglatinWord;
bool truefalse = false;
int letter = 0, wordLength = englishWord.length( );

while (!truefalse && letter < wordLength) 
  {
    if (englishWord.substr(letter,1) == "a" || englishWord.substr(letter,1) == "e" ||englishWord.substr(letter,1) == "i" || englishWord.substr(letter,1) == "o" || englishWord.substr(letter,1) == "u")
        truefalse = true;
    else
        letter++; 
  }
if (letter > wordLength)
    piglatinWord = englishWord + "-way "; 
else
piglatinWord = englishWord.substr(letter, wordLength-letter) + englishWord.substr(0,letter)+ "-ay " ;
cout << piglatinWord; 
}

int main( )
{
ifstream inputFile;
inputFile.open("PigLatinIn.txt");
ofstream outputFile;
outputFile.open("PigLatinOut.txt");
string englishWord, engWords;
bool done = false;
int location;

while(!inputFile.eof())
{
    string englishWord;
    inputFile >> englishWord;
    outputFile << pigLatin(englishWord) << ' ';
}

{
while (!done) 
  {
    location = engWords.find(" "); 
    if (location == -1)
      {
        done = true;
        location = engWords.length( );
      }
    englishWord = engWords.substr(0, location); 
    pigLatin(englishWord); 

    if (!done)
        engWords = engWords.substr(location + 1, engWords.length( ) - location + 1);
  }
}
cout << endl;
inputFile.close();
outputFile.close();
return 0;
}

A:

Your pigLatin function has void for the return type, so it is not returning anything that you might write into the ofstream:
outputFile << pigLatin(englishWord) << ' ';

Change the return type of pigLatin to std::string and add
 return piglatinWord; 

at the end of the function:
string pigLatin(string englishWord)
{
   // ... implementation here
   return piglatinWord;
}

Also, to make your function more clear and uniform, I would suggest you to remove cout << piglatinWord; from the function and output the return value in the caller function:
 englishWord = engWords.substr(0, location); 
 cout << pigLatin(englishWord); 

