Why is string.contains() returning false?

Question

I have the following string: \\\?\hid#vid_04d8pid_003f#62edf110800000#{4d1e55b2-f16f-11cf-88cb-001111000030} stored in a string variable (from a function call) called devPathName

and the following defined: const string myDevice = @"vid_04d8pid_003f";

but the following code always evaluates to false:

Boolean test = true;

test = devPathName.Contains(myDevice);

statusLabel.Text += "\n\tThe value of test: " + test.ToString();

Answer 1

When I stick your code into C#, the compiler doesn't like the "\h" part of your long string. It says, "unrecognized escape sequence". Could that be your problem?

Oh, and if I put a "@" before the long string, the contains() method returns true.

HTH,

-Dan

Answer 2

Assuming that you've already checked for letter "O" vs digit "0" and similar things, I'd suggest that the string you're seeing in the string variable devPathName is being encoded for display and isn't quite what you think it is.

For example, if the string contains the character \x000d (Control-M), the Visual Studio debugger will display this as \r when you inspect the value of the string.

Or, for another example, if the string contains the sequence 3504 (three-five-zero-four) but you instead search for 35O4 (three-five-oh-four) then you'll not find a match.

(Depending on your font, you may not be able to see differences between some characters. Compare "0O1lB8S5" with "0O1lB8S5" in different fonts to see what I mean.)

Answer 3

This returns true for me as well.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            const string myDevice = @"vid_04d8pid_003f";
            string devPathName = @"\\\?\hid#vid_04d8pid_003f#62edf110800000#{4d1e55b2-f16f-11cf-88cb-001111000030}";
            Boolean test =devPathName.Contains(myDevice);
            MessageBox.Show("\n\tThe value of test: " + test.ToString());
        }
    }
}

I guess I would put a breakpoint in and make sure that devPathName isnt being changed on you and that the value is what you expect.

Answer 4

What's evaluating to false, your test variable or part of the display in statusLabel.text? Are you sure the display isn't something like this:

The value of test: false
The value of test: false
The value of test: false
The value of test: false
The value of test: true
The value of test: false

and maybe you're only looking at the first line of that string?

Answer 5

You just need to escape the long string before parsing it via .Contains()

Put an at-symbol (@) at the start of the string, as demonstrated in several of the previous answers and it should evaluate perfectly.

When stepping into .Contains, the initial string, in your case

\\\?\hid#vid_04d8pid_003f#62edf110800000#{4d1e55b2-f16f-11cf-88cb-001111000030}"

contains none-escaped characters and causes .Contains to terminate before it completes the comparison.