How to use special characters in strings like in C#?

[Carl Mercier]

Hi,

Is it possible to use special characters like \n or \t in a VB.NET
string, just like in C#? My guess is NO, but maybe there's something I
don't know.

If it's not possible, does anybody know of a VB.NET function (somebody
must have coded this already) that will interpret strings containings
those special characters, and handle them the same as in C#?

Thanks!

[Herfried K. Wagner [MVP]]

"Carl Mercier" <no****@nospam. com> schrieb:

Is it possible to use special characters like \n or \t in a VB.NET string,
just like in C#? My guess is NO, but maybe there's something I don't know.
No, that's not supported. It's a rare case that you really need a "\n"
inside a string literal. Instead, use 'ControlChars.N ewLine' which will
contain a platform-specific new-line string. 'ControlChars' provides other
characters like 'Cr', 'Lf', and 'Tab' too.

\\\
Dim s As String = _
"Hello" & ControlChars.Ne wLine & _
"World"
///
If it's not possible, does anybody know of a VB.NET function (somebody
must have coded this already) that will interpret strings containings
those special characters, and handle them the same as in C#?

The support for escaped characters in C# string literals is a compiler
feature, which means that it will only work at compile time. The compiler
will replace the escape sequence with the escaped character. C# doesn't
provide a way to perform the unescaping at runtime.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Crouchie1998]

What I tend to do is say:

Dim nl As String = ControlChars.Ne wLine etc. At least then it will shorten
your code quite a lot

Crouchie1998
BA (HONS) MCP MCSE

[Herfried K. Wagner [MVP]]

"Crouchie19 98" <cr**********@s pamcop.net> schrieb:

What I tend to do is say:

Dim nl As String = ControlChars.Ne wLine etc. At least then it will shorten
your code quite a lot

Mhm... I prefer a constant:

\\\
Const NL As String = ControlChars.Ne wLine
///

;-)

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Cor Ligthert]

Herfried,

Mhm... I prefer a constant:

That is an answer *I* like *better*.

You know what I mean probably

:-)

Cor

[Herfried K. Wagner [MVP]]

Cor,

"Cor Ligthert" <no************ @planet.nl> schrieb:

Mhm... I prefer a constant:

That is an answer *I* like *better*.

You know what I mean probably

I have to correct my answer: Using a constant is the "best" solution in
this case:

\\\
Dim t1 As String = "j"
Const t2 As String = "j"
Dim x1 As String = "a" & t1
Dim x2 As String = "a" & t2
///

Corresponding IL code:

\\\
IL_0001: ldstr "j"
IL_0006: stloc.0
IL_0007: ldstr "a"
IL_000c: ldloc.0
IL_000d: call string [mscorlib]System.String:: Concat(string,
string)
IL_0012: stloc.1
IL_0013: ldstr "aj"
IL_0018: stloc.2
///

When using a constant, the compiler will be able to perform the
concatenation at compile time, when using a string variable, the
concatenation is done at runtime.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[Carl Mercier]

Hi,

I know about .NewLine, but I need to store strings in a file (on a
single line), and I wanted to make use of special characters like in C#.
IMO, this difference with C# is pretty stupid. MS should allow us to
use it in VB as well.

If anyone knows of a VB function that will convert strings with special
characters like \n to a string with a .NewLine character in there, that
would be great.

EX:

Original: "Hello\nWor ld!" gets converted to "Hello" + NewLine + "World"

Herfried K. Wagner [MVP] wrote:

"Carl Mercier" <no****@nospam. com> schrieb:

Is it possible to use special characters like \n or \t in a VB.NET
string, just like in C#? My guess is NO, but maybe there's something I
don't know.

No, that's not supported. It's a rare case that you really need a "\n"
inside a string literal. Instead, use 'ControlChars.N ewLine' which will
contain a platform-specific new-line string. 'ControlChars' provides
other characters like 'Cr', 'Lf', and 'Tab' too.

\\\
Dim s As String = _
"Hello" & ControlChars.Ne wLine & _
"World"
///

If it's not possible, does anybody know of a VB.NET function (somebody
must have coded this already) that will interpret strings containings
those special characters, and handle them the same as in C#?

The support for escaped characters in C# string literals is a compiler
feature, which means that it will only work at compile time. The
compiler will replace the escape sequence with the escaped character.
C# doesn't provide a way to perform the unescaping at runtime.

[Herfried K. Wagner [MVP]]

"Carl Mercier" <no****@nospam. com> schrieb:

I know about .NewLine, but I need to store strings in a file (on a single
line), and I wanted to make use of special characters like in C#. IMO,
this difference with C# is pretty stupid. MS should allow us to use it in
VB as well.
You need to separate between compiler behavior and reading data from a file.
C# doesn't have any advantages in the latter case, if the file contains the
string "\r\n", the sequence of characters "\", "r", "\", "n" will be
contained in the string, not a 'CRLF' sequence.
If anyone knows of a VB function that will convert strings with special
characters like \n to a string with a .NewLine character in there, that
would be great.

You will have to do the replacement yourself, the same way as you have to do
it in C#.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>

[David]

On 2005-04-23, Herfried K. Wagner [MVP] <hi************ ***@gmx.at> wrote:

"Carl Mercier" <no****@nospam. com> schrieb:

Is it possible to use special characters like \n or \t in a VB.NET string,
just like in C#? My guess is NO, but maybe there's something I don't know.

No, that's not supported. It's a rare case that you really need a "\n"
inside a string literal. Instead, use 'ControlChars.N ewLine' which will
contain a platform-specific new-line string.

Is that actually documented someplace, that NewLine will return a
platform-specific string? Does anyone know if mono does this (I've
never used the vb stuff in mono)?

[Jay B. Harlow [MVP - Outlook]]

Carl,
| Is it possible to use special characters like \n or \t in a VB.NET
| string, just like in C#?
As the others have pointed out \n & \t are a compile time feature of C#, not
a runtime feature.
It sounds like you want a runtime feature that will convert the C# escape
sequences into valid chars. I don't know how complete it is, RegEx.Unescape
will unescape most if not all of the C# escape sequences.

http://msdn.microsoft.com/library/de...scapetopic.asp
Alternatively I would consider using a RegEx.Replace with a MatchEvaluator
function.

Something like:

Private Shared Function EscapeCharacter s(ByVal match As Match) As String
Select Case match.Value
Case "\b"
Return ControlChars.Ba ck
Case "\t"
Return ControlChars.Ta b
Case "\r"
Return ControlChars.Cr
Case "\v"
Return ControlChars.Ve rticalTab
Case "\f"
Return ControlChars.Fo rmFeed
Case "\n"
Return ControlChars.Lf
Case Else
Return match.Value.Sub string(1)
End Select
End Function

Const pattern As String = "\\."
Static parser As New Regex(pattern, RegexOptions.Co mpiled)

Dim input As String
Dim output As String
input = parser.Replace( input, AddressOf EscapeCharacter s)

The advantage of RegEx.Replace is you have control over how the escape
sequences are defined. For example you could use {Back}, {Tab}, {Cr}, ...
instead.

With effort it should be easy to add support for octal (\040), hex (\x20),
control (\cC), unicode (\u0020) sequences.

Hope this helps
Jay

"Carl Mercier" <no****@nospam. com> wrote in message
news:%2******** ********@TK2MSF TNGP09.phx.gbl. ..
| Hi,
|
| Is it possible to use special characters like \n or \t in a VB.NET
| string, just like in C#? My guess is NO, but maybe there's something I
| don't know.
|
| If it's not possible, does anybody know of a VB.NET function (somebody
| must have coded this already) that will interpret strings containings
| those special characters, and handle them the same as in C#?
|
| Thanks!