is char unicode?

[Claire]

Hi
I thought chars were unicode nowadays. If so then why does the following
return 1 as size of the struct please.

using System.Runtime.InteropServices;
public struct s
{
public char j;
}

private void Form1_Load(object sender, EventArgs e)
{
s ss = new s();
Text = Marshal.SizeOf(ss).ToString();
}

 

[Mads Bondo Dydensborg]

Hi
I thought chars were unicode nowadays. If so then why does the following
return 1 as size of the struct please.

A guess: You marshal to some encoding, that is able to use a single byte for
some chars. Example: utf8.

Regards,

Mads

--
Med venlig hilsen/Regards

Systemudvikler/Systemsdeveloper cand.scient.dat, Ph.d., Mads Bondo
Dydensborg
Dansk BiblioteksCenter A/S, Tempovej 7-11, 2750 Ballerup, Tlf. +45 44 86 77
34

 

[Claire]

A guess: You marshal to some encoding, that is able to use a single byte
for
some chars. Example: utf8.

I havent set any encoding, the sample code is what I used in a new
application. I'm a bit confused why the size of the struct is 1 rather than
2 if the visual studio help hint that appears when my mouse passes over
"char" says "struct system.char represents a unicode character"

I'm creating some byte[] arrays of data to write to smartcards and need to
know how to create a struct that defines unicode char[] arrays rather than 1
byte char[] arrays

 

[Jon Skeet [C# MVP]]

I thought chars were unicode nowadays. If so then why does the following
return 1 as size of the struct please.

It's not returning 1 as the size of the struct - it's returning 1 as
the size of the *marshalled* data, for situations where it's
marshalled to unmanaged code.

If you use the sizeof(...) operator it will return 2.

Jon

 

[Claire]

If you use the sizeof(...) operator it will return 2.

Jon

Thanks Jon

 

[Mads Bondo Dydensborg]

I havent set any encoding,

Whenever you Marshal something, an encoding is implied. At least, that is
how I understand it.

Regards,

Mads

--
Med venlig hilsen/Regards

Systemudvikler/Systemsdeveloper cand.scient.dat, Ph.d., Mads Bondo
Dydensborg
Dansk BiblioteksCenter A/S, Tempovej 7-11, 2750 Ballerup, Tlf. +45 44 86 77
34

 

[Claire]

Thanks very much Mads

 

[Willy Denoyette [MVP]]

Hi
I thought chars were unicode nowadays. If so then why does the following
return 1 as size of the struct please.

using System.Runtime.InteropServices;
public struct s
{
public char j;
}

private void Form1_Load(object sender, EventArgs e)
{
s ss = new s();
Text = Marshal.SizeOf(ss).ToString();
}

This is because Marshal.SizeOf returns the size of the marshaled structure
AND because char is marshaled as Ansi by default.
If you want to marshal chr's as Unicode you'll have to set the CharSet
attribute, like:

[ StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct s
{
public char j;
}

for above Marshal.SizeOf will return 2.

Willy.