Question

I have some 100 files in which I need to replace:

1. Eval(“something”) with Eval(“something”).ToEncodedString()
2. Eval(“something”).ToString() with Eval(“something”).ToEncodedString()

I’m writing a small C# application that can automate this. But unable to form the regular expression. Would somebody help me please?

Answer 1

You can use this pattern: @"\bEval\(""(?<Value>.+?)""\)(?:\.ToString\(\))?"

Breakdown:

• \bEval: match a word-boundary to ensure we match “Eval” as a whole word and not as part of another word
• \("": literal opening parenthesis and double quotes (the double quotes appear twice since that’s how they’re escaped when using a verbatim string literal, i.e., the @ symbol preceding the string)
• (?<Value>.+?): named capture group of “Value” which is a non-greedy match of any character (will stop at double quotes)
• ""\): closing double quotes and closing parenthesis
• (?:\.ToString\(\))?: the (?:...) bit is a non-capturing group, then we match .ToString() literally with appropriate escaping, and the final ? makes this group optional

The replacement pattern is @"Eval(""${Value}"").ToEncodedString()", which is easy to understand. The important part is that the named capture group, “Value,” is referenced by using ${Value}.

Example code:

string[] inputs = 
{
    @"Eval(""something"")",
    @"Eval(""hello"").ToString()"
};

string pattern = @"\bEval\(""(?<Value>.+?)""\)(?:\.ToString\(\))?";
string replacement = @"Eval(""${Value}"").ToEncodedString()";

foreach (var input in inputs)
{
    Console.WriteLine(Regex.Replace(input, pattern, replacement));
}