Is there an alternative to string.Replace that is case-insensitive?


I need to search a string and replace all occurrences of %FirstName% and %PolicyAmount% with a value pulled from a database. The problem is the capitalization of FirstName varies. That prevents me from using the String.Replace() method. I've seen web pages on the subject that suggest

Regex.Replace(strInput, strToken, strReplaceWith, RegexOptions.IgnoreCase);

However for some reason when I try and replace %PolicyAmount% with $0, the replacement never takes place. I assume that it has something to do with the dollar sign being a reserved character in regex.

Is there another method I can use that doesn't involve sanitizing the input to deal with regex special characters?

8/9/2017 3:53:04 AM

Accepted Answer

$0 - "Substitutes the last substring matched by group number number (decimal)."

In .NET Regular expressions group 0 is always the entire match. For a literal $ you need to

string value = Regex.Replace("%PolicyAmount%", "%PolicyAmount%", @"$$0", RegexOptions.IgnoreCase);
10/28/2008 7:47:10 PM

Seems like string.Replace should have an overload that takes a StringComparison argument. Since it doesn't, you could try something like this:

public static string ReplaceString(string str, string oldValue, string newValue, StringComparison comparison)
    StringBuilder sb = new StringBuilder();

    int previousIndex = 0;
    int index = str.IndexOf(oldValue, comparison);
    while (index != -1)
        sb.Append(str.Substring(previousIndex, index - previousIndex));
        index += oldValue.Length;

        previousIndex = index;
        index = str.IndexOf(oldValue, index, comparison);

    return sb.ToString();

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