Simple Parser Program

I have *just* started on working with C++ and i am interested in what the fellow forumers think of my Test Parser program :).

(I have experience with PHP from before.)

File: main.cpp, Executable Download

Code:

---

#include <cstdlib>
#include <iostream>
#include <fstream>
#include <string>
//Maybe not be needed
#include <algorithm>
#include <cctype>



using namespace std;




string StringToLower(string strToConvert)
{//change each element of the string to lower case
  for(int i=0;i<strToConvert.length();i++)
  {
      strToConvert[i] = tolower(strToConvert[i]);
  }
  return strToConvert;//return the converted string
}



void BreakLine ( )
{
  cout << "\n";
}

void PrintItOut(string eOutputText)
{
  cout << "\"" << eOutputText << "\"" << endl;
}

void Parse()
{
  //INIT
  string Line = "";
  string cParseLine = "";
  char cParseCharacter;
  char cParseCharacterPrev = '\0';
  char cParseCharacterNext = '\0';
  string FullString = "";
  bool ParseString = 0;
  bool NoEndLine = 0;
  bool CParserContinue = 1;
 
  int FunctionType = 0;
 
  int cPos = 0;
  int cLength = 0;
 
  ifstream fFile ("parse.txt");
 
  while (! fFile.eof() )
  {
  getline(fFile, Line);
  FullString.append(Line);
  }
  fFile.close();
 
  cLength = FullString.length();
  //PARSE!
  while (cPos < cLength)
  {
  //Get character; and look for escaping
  cParseCharacterPrev = cParseCharacter;
  cParseCharacter = FullString[cPos];
  cParseCharacterNext = FullString[cPos + 1];
  //cout << cParseCharacterPrev << cParseCharacter << cParseCharacterNext << " ";
 
  //Check if valid
      if(ParseString == 0 && cParseCharacter != '\t' && cParseCharacter != ' ' )
      {
      cParseLine += cParseCharacter;
        //////////////////////////////////////////////////
        //
        //  PRINT TEXT
        //
        //////////////////////////////////////////////////
        if ( StringToLower(cParseLine) == "print")
        {
          //Parse String now.
          ParseString = 1;
          //Empty the Line
          cParseLine.erase();
          cPos++;
        }
        //////////////////////////////////////////////////
        //
        //  LINE BREAK
        //
        //////////////////////////////////////////////////
        if ( StringToLower(cParseLine) == "break" && cParseCharacterNext == ';')
        {
          //Parse String now.
          //ParseString = 1;
          //Empty the Line
          BreakLine();
          cParseLine.erase();
          cPos++;
        }
        //////////////////////////////////////////////////
        //
        //  PAUSE
        //
        //////////////////////////////////////////////////
        if ( StringToLower(cParseLine) == "pause" && cParseCharacterNext == ';')
        {
          //Parse String now.
          //ParseString = 1;
          //Empty the Line
          BreakLine();
          cParseLine.erase();
          cPos++;
          system("pause");
          BreakLine();
        }
        //////////////////////////////////////////////////
        //
        //  CLEAR SCREEN
        //
        //////////////////////////////////////////////////
        if ( StringToLower(cParseLine) == "clear" && cParseCharacterNext == ';')
        {
          //Parse String now.
          //ParseString = 1;
          //Empty the Line
          system("cls");
          cParseLine.erase();
          cPos++;
        }
        //////////////////////////////////////////////////
        //
        //  EXIT
        //
        //////////////////////////////////////////////////
        if ( StringToLower(cParseLine) == "exit" && cParseCharacterNext == ';')
        {
          //Parse String now.
          //ParseString = 1;
          //Empty the Line
          BreakLine();
          cParseLine.erase();
          exit(1);
        }
      }else if (ParseString == 1){
       
       
       
        if (cParseCharacter == '\\')
        {
          //Nothing, if not next is it
          if (cParseCharacterNext == '\\')
          {
            cParseLine += cParseCharacter;
            CParserContinue = 1;
            //cParseCharacter = '\\';
            cPos ++;
            cParseCharacter = cParseCharacterNext;
            CParserContinue = 0;
          }
          if (cParseCharacterNext == ';')
          {
            NoEndLine = 1;
            CParserContinue = 1;
            cParseCharacter = '\0';
            cPos++;
            cParseCharacter = cParseCharacterNext;
          }
         
        }
       
       
        if ( cParseCharacter == ';' && NoEndLine != 1 )
        {
          //Parse String now.
          //Do stuff
          if(FunctionType == 0)
          {
            PrintItOut(cParseLine);
            cParseLine.erase();
          }
          CParserContinue = 0;
          ParseString = 0;
          }
         
          if (CParserContinue == 1)
          {
            cParseLine += cParseCharacter;
          }
        //End String Parsing   
        }
      NoEndLine = 0;
      CParserContinue = 1;
      cPos++;
      }
 
}

int main(int argc, char *argv[])
{
    system("PAUSE");
    cout << "\nParse!\n\n";
    Parse();
    cout << "\nEnd of Parse!\n\n";
    system("PAUSE");
    return EXIT_SUCCESS;
}

---

What could be optimised here? Or should i rewrite the parser from the beginning? (I am just making this parser to learn C++ and make use of it in games :). )

The compiler and program i use: Bloodshed Dev-C++ with mingw compiler.

Not bad as a first try :)

I'd suggest changing this though

Code:

---

  while (! fFile.eof() )
  {
  getline(fFile, Line);
  FullString.append(Line);
  }
  fFile.close();

---

You may have been taught to use the idiom "Read until EOF", although this doesn't work in C++, because the EOF flag isn't set until after a failed read attempts to go past the end of the file (So your final call to getline(fFile, Line) will fail)

The correct idiom in C++ is "Read while the file has content", which looks like this

Code:

---

  while ( getline(fFile, Line) )
  {
    FullString.append(Line);
  }
  fFile.close();

---

The final call to getline (The one which fails) will cause your while loop to stop there and then, rather than continuing to call FullString.append(Line);

Thanks for the correction :). Anything more i should think of when making parsers than just make them flexible?

You seem to be going cParseCharacterNext == ';' a lot. Perhaps you could wrap a larger if statement around those if statements that have this expression.

Also, in at least one place you're comparing a bool against 1 or 0:

Code:

---

NoEndLine != 1

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It's standard practice to use true and false when referring to the values of bools, rather than 1 and 0. But 1 and 0 works, too, of course.

Just Programmer preference :d.