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How can I remove all commas not in brackets from a string in C #?

I have a math analyzer that can do functions like "IntPow (3,2)". If the user inserts "1,000,000" and then adds a plus sign, creating the complete equation "1,000,000 + IntPow (3,2)", the parser fails because it does not work with numbers containing commas.

I need to remove commas from "1,000,000" but not from "IntPow (3,2)" because IntPow has two parameters separated by comma. The final equation will be "1,000,000 + IntPow (3.2)". The equation is stored on one line. How would I remove only the commas that are outside the parentheses? I am assuming and saying that numbers containing commas will not be put into the IntPow parameter list.

When I say "remove commas" I really want to remove "CultureInfo.CurrentCulture.NumberFormat.NumberGroupSeparator" which can be a comma or a period depending on local. This part will be simple because I am assuming that RegEx will be used and I can just concatenate that value in the RegEx comma.

I have this RegEx: (. *?) For finding parentheses and values ​​inside them, but I'm not sure how to remove only commas outside of RegEx matches.

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4 answers


The easiest way is not to try to make a regex. Just iterate over the string one character at a time. If you are reading '(', increase the counter. If you are reading ')', decrease this counter. If you are reading a comma, remove it if the counter is 0, otherwise leave it alone.



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But what if the user inserts:

1,000+IntPow(3,000,2,000)


Now 3000 is between the commas.

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Sub Main()

    '
    '   remove Commas from a string containing expression-like syntax
    '       (eg.  1,000,000 + IntPow(3,2) - 47 * Greep(9,3,2) $ 5,000.32 )
    '       should become:  1000000 + IntPow(3,2) - 47 * Greep(9,3,2) $ 5000.32
    '

    Dim tInput As String = "1,000,000 + IntPow(3,2) - 47 * Greep(9,3,2) $ 5,000.32"
    Dim tChar As Char = Nothing
    Dim tResult As StringBuilder = New StringBuilder(tInput.Length)
    Dim tLevel As Integer = 0

    For Each tChar In tInput
        Select Case tChar
            Case "("
                tLevel += 1
                tResult.Append(tChar)

            Case ")"
                tLevel -= 1
                tResult.Append(tChar)

            Case ","   '  Change this to your separator character.
                If 0 < tLevel Then
                    tResult.Append(tChar)
                End If

            Case Else
                tResult.Append(tChar)

        End Select
    Next

    Console.ForegroundColor = ConsoleColor.Cyan
    Console.WriteLine(tInput)
    Console.WriteLine(String.Empty)
    Console.ForegroundColor = ConsoleColor.Yellow
    Console.WriteLine(tResult.ToString)
    Console.WriteLine()
    Console.ResetColor()
    Console.WriteLine(" -- PRESS ANY KEY -- ")
    Console.ReadKey(True)

End Sub
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I don't think this is possible with regular expressions. The distinction between inner and outer parentheses is not common language. It is a context insensitive language that cannot be solved using a normal state machine (expression). You need a stack machine (i.e. Something Chad related)

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