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how to make string returned by ResourceManager.GetString not verbatim

Okay, I have a string
string textToShow = "this\nrocks"
which when put in label in winforms window will then show
this
rocks
Which is the result I'd like to get. Now, instead of setting the textToShow in the code, I set it in the resource file. When I tried to get the value from resource file using
Properties.Resources.ResourceManager.GetString("textToShow");
the whole string instead will be treated as verbatim, showing
this\nrocks
when put in a label in a winforms window. This is not the result i'm looking for. What's the best way to store strings with special characters in resource file then? I can do string replace for every special characters, like
string.Replace(#"\n", "\n");
but then I need to replace every special characters whenever I call method ResourceManager.GetString, which I think is not the most elegant solution. If there is some ways to make string returned from method ResourceManager.GetString not verbatim, please do tell me.
Thanks

This was already answered here: StackOverflow: How to deal with newline
Basically you have two useful options:
Use shift + enter in the resource manager text editer to add a new line.
Or use String.Format() to replace {0} with \n on read.

The .Net 4.5 framework has the unescape functionality as shown here:
using System.Text.RegularExpressions;
Regex.Unescape(Properties.Resources.ResourceManager.GetString("textToShow"));
solves your issue. Now you can use \n and \u in the resource files.

On the resource editor type "this<shift+enter>rocks" as the resource value.

HttpRequestValidationException workaround

I have a textbox that when user inputs a string such as "<daily" (to signify less than daily) it throws a HttpRequestValidationException. However if there is a space between the less than symbol and the string, it works fine such as "< daily".
I have had it change the value that is submitted in the code behind by using the replace function. For example:
string s = "This is a <test";
if(s.Contains("<")){
s = s.Replace("<", "< "); //I have also used "<" & "<"
}
However, I still get the exception because in the textbox it is still showing it as "<daily". I am wondering if there is a way that if the focus is off the textbox to dynamically add a space to the string?
I understand that the HttpRequestValidationException is not supposed to allow those characters, but it seems to allow if there are spaces. Any thoughts?

It would be nice to know how you use the string in the HttpRequest. Depending on how and where you use we could come up with some ideas.

Windows forms textbox or c# string native method for checking non-alphanumeric character

Is there a windows form textbox or c# string native member method that checks if its contents have any non-alphanumeric character?
or do I have to do it manually?
EDIT:
I used #Habib's answer and added so that white spaces are checked as well, and to my surprise, it worked! lol
bool result = strVariable.Any(r=> (!char.IsLetterOrDigit(r) && !char.IsWhiteSpace(r)));
Btw, I've never used the "lambda" expression that's why I'm surprised the code above worked when I added the whitespace condition on #Habib's initial answer.

You can use char.IsLetterOrDigit
Indicates whether a Unicode character is categorized as a letter or a
decimal digit.
bool result = strVariable.Any(r=> !char.IsLetterOrDigit(r));

You can create a control which has TextBox as its base, but currently there are no properties which does this for you, you have to do this on the KeyUp event of the textBox and use a regex or similar

How to produce a soft return using C#.net

I know this is kind of easy question but i cant seem to find it anywhere. Is there someone out there who knows how to create a soft return inside a set of text using C#.net?
I need to print soft return to a text file/xml file. this text file will be generated using c#.net. you could verify if the answer is correct if you use NOTEPAD++ then enable the option to “View>Show Symbol > Show End of Line” then you will see a symbol like this:
Thanks in advance :)

Not sure what you mean by a soft return. A quick Google search says it's a non-stored line break typically due to word wrapping in which case you wouldn't actually put this in a string, it would only be relevant when the string was rendered for display.
To put a carriage return and/or line feed in the string you would use:
string s = "line one\r\nline two";
And for further reference, here are the other escape codes that you can use.
Link (MSDN Blogs)
In response to your edit
The LF that you see can be represented with \n in a string. Obviously you have a specific line ending sequence that you need to represent. If you were to use Environment.NewLine that is going to give you different results on different platforms.

var message = $"Tom{Convert.ToChar(10)}Harry";
Results in:
Tom
Harry
With just a line feed between.

Lke already mentioned you can use Enviroment.NewLine but I am not sure if that i what you want or if you are actually trying to append a ASCII 141 to your string as mentioned in the comments.
You can add ASCII chr sequences to your string like this.
var myString = new StringBuilder("Foo");
myString.Append((char)141);

.NET string IndexOf unexpected result

A string variable str contains the following somewhere inside it: se\">
I'm trying to find the beginning of it using:
str.IndexOf("se\\\">")
which returns -1
Why isn't it finding the substring?
Note: due to editing the snippet showed 5x \ for a while, the original had 3 in a row.

Your code is in fact searching for 'se\\">'. When searching for strings including backslashes I usually find it easier to use verbatim strings:
str.IndexOf(#"se\"">")
In this case you also have a quote in the search string, so there is still some escaping, but I personally find it easier to read.
Update: my answer was based on the edit that introduced extra slashes in the parameter to the IndexOf call. Based on current version, I would place my bet on str simply not containing the expected character sequence.
Update 2:
Based on the comments on this answer, it seems to be some confusion regarding the role of the '\' character in the strings. When you inspect a string in the Visual Studio debugger, it will be displayed with escaping characters.
So, if you have a text box and type 'c:\' in it, inspecting the Text property in the debugger will show 'c:\\'. An extra backslash is added for escaping purposes. The actual string content is still 'c:\' (which can be verified by checking the Length property of the string; it will be 3, not 4).
If we take the following string (taken from the comment below)
" '<em
class=\"correct_response\">a
night light</em><br
/><br /><table
width=\"100%\"><tr><td
class=\"right\">Ingrid</td></tr></table>')"
...the \" sequences are simply escaped quotation marks; the backslashes are not part of the string content. So, you are in fact looking for 'se">', not 'se\">'. Either of these will work:
str.IndexOf(#"se"">"); // verbatim string; escape quotation mark by doubling it
str.IndexOf("se\">"); // regular string; escape quotation mark using backslash

This works:
string str = "<case\\\">";
int i = str.IndexOf("se\\\">"); // i = 3
Maybe you're not correctly escaping one of the two strings?
EDIT there's an extra couple of \ in the string you are searching for.

Maybe the str variable does not actually contain the backslash.
It may be just that when you mouse over the variable while debugging, the debugger tooltip will show the escape character.
e.g. If you put a breakpoint after this assignment
string str = "123\"456";
the tooltip will show 123\"456 and not 123"456.
However if you click on the visualize icon, you will get the correct string 123"456

Following code:
public static void RunSnippet()
{
string s = File.ReadAllText (#"D:\txt.txt");
Console.WriteLine (s);
int i = s.IndexOf("se\\\">");
Console.WriteLine (i);
}
Gives following output:
some text before se\"> some text after
17
Seems like working to me...

TextBox2.Text = TextBox1.Text.IndexOf("se\"">")
seems to work in VB.

DoubleQuotes within a string need to be specified like "" Also consider using verbatim strings - So an example would be
var source = #"abdefghise\"">jklmon";
Console.WriteLine(source.IndexOf(#"se\"">")); // returns 8

If you are looking for se\">
then
str.IndexOf(#"se\"">")
is less error-prone. Note the double "" and single \
Edit, after the comment: it seems like the string may contain ecaping itself, in which case in se\"> the \" was an escaped quote, so the literal text is simply se"> and the string to use is Indexof("se\">")