Question

I’m writing an app in C# which allows the user to perform database queries based on file names.

I’m using the Regex.Replace(string, MatchEvaluator) overload to perform replacements, because I want the user to be able to have replacement strings like SELECT * FROM table WHERE record_id = trim($1) even though the DB we’re using doesn’t support functions like trim().

What I don’t want is to do a series of replacements where if the value of $1 contains “$2”, both replacements occur. How do I perform several string replacements in one go? I know PHP’s str_replace supports arrays as arguments; is there a similar function for C#?

Answer 1

There’s nothing built-in, but you could try something like this:

string foo = "the fish is swimming in the dish";

string bar = foo.ReplaceAll(
    new[] { "fish", "is", "swimming", "in", "dish" },
    new[] { "dog", "lies", "sleeping", "on", "log" });

Console.WriteLine(bar);    // the dog lies sleeping on the log

// ...

public static class StringExtensions
{
    public static string ReplaceAll(
        this string source, string[] oldValues, string[] newValues)
    {
        // error checking etc removed for brevity

        string pattern =
            string.Join("|", oldValues.Select(Regex.Escape).ToArray());

        return Regex.Replace(source, pattern, m =>
            {
                int index = Array.IndexOf(oldValues, m.Value);
                return newValues[index];
            });
    }
}