Question

How can I escape certain characters in a string with a C# Regex?

This is a test for % and ' thing? -> This is a test for \% and \' thing?

Answer 1

resultString = Regex.Replace(subjectString, 
    @"(?<!      # Match a position before which there is no
     (?<!\\)    # odd number of backlashes
     \\         # (it's odd if there is one backslash,
     (?:\\\\)*  # followed by an even number of backslashes)
    )
    (?=[%'])    # and which is followed by a % or a '", 
    @"\", RegexOptions.IgnorePatternWhitespace);

However, if you’re trying to protect yourself against malevolent SQL queries, regex is not the right way to go.