C＃正则表达式中的“ Enter”问题

Question

There I have an issue on regex expression in C#, Code:

// For 1D barcode scanner
Regex regex = new Regex("^(.*)\x0D$", RegexOptions.Compiled);
var match = regex.Match("1234\r");

The match.Success is true. Then I change the code as following:

 // For 2D barcode scanner
 Regex regex = new Regex("^(.*)$", RegexOptions.Compiled);
 var match = regex.Match("1234\r");

The match.Success is still true(Expect false). I don't know where is error.

Actually, the string "1234\\r" is a result of a 1D barcode scanner, the suffix of 1D barcode scanner is "\\x0D" in my software, but the suffix of 2D barcode scanner is null in my software.I think it must be something wrong on regex expression for 2D barcode.

Answer 1

With default settings, $ is interpreted as the end of the input string, rather than the end of a line. This will allow your .* to match against any trailing whitespace that might be added.

If you wish to exclude this, you can do so with a character class, like this ^([^\\r]*)$

Answer 2

I use another work round for this case, code as bellow:

 if (string.IsNullOrEmpty(Prefix) && string.IsNullOrEmpty(Suffix))  
    regex = new Regex("^[a-z0-9!\"#$%&'()*+,.\\/:;<=>?@\\[\\] ^_`{|}~-]*$", RegexOptions.Compiled);
 else
     {
       regex = new Regex($"^{this.Prefix}(.*){this.Suffix}$", RegexOptions.Compiled);
     }

It means that if the suffix and prefix is null or empty, I use a regex to match "all printable charters".