Question

This is a very basic regex question, but I’m not quite sure where I am going wrong.

I am attempting to take an input string such as this:

string exp = @"$a$ + $ab$";

Match the pattern $....$ and replace that value in the original string. For example, I want to substitute the number 1 for $a$ and the number 2 for $ab$, so my final string would look like "1 + 2".

What I have setup is the following function:

private string SubstituteStandardValues(string exp)
{
    //Find Std values w/Regex
    Match match = Regex.Match(exp, @"/\($.*$\)/s", RegexOptions.IgnoreCase);

    if (match.Success)
    {
        foreach (var m in match.Groups)
        {
            //Do string replace logic here!
        }
    }
    return exp;
}

My problem is match is always false, which leads me to believe that my regex is incorrect.

Where have I gone astray? Thanks for the help!

Answer 1

Try using this code:

public string SubstituteStandardValues(string exp)
{
    var matches = Regex.Matches(exp, @"\$[a-z]+\$", RegexOptions.IgnoreCase);

    foreach (Match match in matches)
    {
        // replace logic here...
    }

    return exp;
}