infix to postfix converter

Question

Hi.

I have been working on this infix to postfix/polis notation converter. Although, I do not feel the solution is adequate. Specifically the j (EDIT: Now called index) variable is bugging me.

Do you guys have any suggestions? Or perhaps there is a much better way to accomplish it? Or do I just worry too much?

public static string[] InfixToPostfix(string[] infixArray)
{
    var stack = new Stack<string>();
    var postfix = new string[infixArray.Length];

    int index = 0;
    string st;
    for (int i = 0; i < infixArray.Length; i++)
    {
        if (!(MyMath.MathOperators.Contains(infixArray[i])))
        {
            postfix[index] = infixArray[i];
            index++;
        }
        else
        {
            if (infixArray[i].Equals("("))
            {
                stack.Push("(");
            }
            else if (infixArray[i].Equals(")"))
            {
                st = stack.Pop();
                while (!(st.Equals("(")))
                {
                    postfix[index] = st;
                    index++;
                    st = stack.Pop();
                }
            }
            else
            {
                while (stack.Count > 0)
                {
                    st = stack.Pop();
                    if (RegnePrioritet(st) >= RegnePrioritet(infixArray[i]))
                    {
                        postfix[index] = st;
                        index++;
                    }
                    else
                    {
                        stack.Push(st);
                        break;
                    }
                }
                stack.Push(infixArray[i]);
            }
        }
    }
    while (stack.Count > 0)
    {
        postfix[index] = stack.Pop();
        index++;
    }

    return postfix.TakeWhile(item => item != null).ToArray();
}

Answer 1

If you replace 'array' by a Stack, you don't have to keep track where you are with the 'index' variable.

You can then return your result with postfixStack.ToArray()

My implementation:

public static string[] InfixToPostfix( string[] infixArray )
{
 var stack = new Stack<string>();
 var postfix = new Stack<string>();

 string st;
 for ( int i = 0 ; i < infixArray.Length ; i++ )
 {
  if ( !( "()*/+-".Contains( infixArray[ i ] ) ) )
  {
   postfix.Push(infixArray[i]);
  }
  else
  {
   if ( infixArray[ i ].Equals( "(" ) )
   {
    stack.Push( "(" );
   }
   else if ( infixArray[ i ].Equals( ")" ) )
   {
    st = stack.Pop();
    while ( !( st.Equals( "(" ) ) )
    {
     postfix.Push( st );
     st = stack.Pop();
    }
   }
   else
   {
    while ( stack.Count > 0 )
    {
     st = stack.Pop();
     if ( RegnePrioritet( st ) >= RegnePrioritet( infixArray[ i ] ) )
     {
      postfix.Push(st);
     }
     else
     {
      stack.Push( st );
      break;
     }
    }
    stack.Push( infixArray[ i ] );
   }
  }
 }
 while ( stack.Count > 0 )
 {
  postfix.Push(stack.Pop());
 }

 return postfix.Reverse().ToArray();
}

Answer 2

RegnePrioritet? what does that mean?

Answer 3

What the Hell is RegnePrioritet ? And what does it do ?