C# String Length returning the wrong amount

Question

I have a string of 13 characters. 8C4B99823CB9C. I am assigning it to a string.

 string serialNumber = "‭8C4B99823CB9C‬";

This string then enters a method

GenerateCode(proxy, serialNumber, product);

Inside this method I have this line...

codeSerial = serial_no.Substring(serial_no.Length - codeSerialLength, codeSerialLength);

In the watch this is showing the length as 15.

Here is the full code

[TestMethod]
public void CanGenerateCodeNumberWithPrefixWithHEX()
{
    string serialNumber = "‭8C4B99823CB9C‬";
    Entity product = new Entity();
    product.Attributes["piv_codeseriallength"] = 8;
    product.Attributes["piv_codeprefix"] = "G";
    string result = GenerateCode(proxy, serialNumber, product);
    string expected = "G9823CB9C";
    Assert.AreEqual(expected, result, "The Code was not generated correctly");
}

public static string GenerateCode(IOrganizationService _service, string serial_no, Entity product)
{
    string codeSerial = null;
    //Serial Length
    if (product.Attributes.ContainsKey("piv_codeseriallength"))
    {
        codeSerial = serial_no;
        int codeSerialLength = product.GetAttributeValue<int>("piv_codeseriallength");
        codeSerial = serial_no.Substring(serial_no.Length - codeSerialLength, codeSerialLength);
        string prefix = product.Attributes.ContainsKey("piv_codeprefix") ? product.GetAttributeValue<string>("piv_codeprefix") : "";
        codeSerial = prefix + codeSerial;
    }
    return codeSerial;
}

This unit test fails because it thinks the string is 15 characters long and so taking the wrong section of the string

Answer 1

You have hidden unicode characters in your string. One good way to find out is to copy&paste the full string into a text editor, then try to move the caret left and right along the string. You'll see that you need to press left or right twice around the quotes, meaning that there's more characters then meet the eye. Of course, another way would be simply to open the string in a hexadecimal editor.

Assuming you only need simple characters, you can sanitize your input with a regex, to strip the extra characters:

var sanitizedInput = Regex.Replace(input, @"[^\w:/ ]", string.Empty);