sizeof(), C# and managed code

[Paul]

I'm porting a C++ function which reads a file in binary mode, sometimes
reading 2 bytes into an unsigned short, 4 bytes into a long, etc into a C#
implementation. When using the FileStream.Read function, I'd like to code
it to read the size of a C# ushort, for example. The documentation says the
sizeof() is only supported in unsafe mode. Is there any equivalent to
sizeof() that I can use in managed code?

[Thobias Jones]

Hi Paul,

If you use BinaryReader, you have several methods to read in various
size value types, such as ReadInt16, ReadInt32, ReadDouble, etc.

Thobias Jones
Paul wrote:

I'm porting a C++ function which reads a file in binary mode, sometimes
reading 2 bytes into an unsigned short, 4 bytes into a long, etc into a C#
implementation. When using the FileStream.Read function, I'd like to code
it to read the size of a C# ushort, for example. The documentation says the
sizeof() is only supported in unsafe mode. Is there any equivalent to
sizeof() that I can use in managed code?

[Pieter Philippaerts]

"Paul" <no************ *****@i-stat.com> wrote

The documentation says the
sizeof() is only supported in unsafe mode. Is there any equivalent to
sizeof() that I can use in managed code?

Try the Marshal.SizeOf( ) method (from the System.Runtime. InteropServices
namespace).

Regards,
Pieter Philippaerts

[Jared Parsons [MSFT]]

You shouldn't use Marshal.SizeOf( ) for this operation. I assume that Paul
is trying to read managed types from the file. Marshal.SizeOf( ) will give
you the unmanaged size which may not be equal to
managed size.

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ja******@online .microsoft.com
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"Paul" <no************ *****@i-stat.com> wrote

The documentation says the
sizeof() is only supported in unsafe mode. Is there any equivalent to
sizeof() that I can use in managed code?

Try the Marshal.SizeOf( ) method (from the System.Runtime. InteropServices
namespace).

Regards,
Pieter Philippaerts

[Jon Skeet [C# MVP]]

Paul <no************ *****@i-stat.com> wrote:

I'm porting a C++ function which reads a file in binary mode, sometimes
reading 2 bytes into an unsigned short, 4 bytes into a long, etc into a C#
implementation. When using the FileStream.Read function, I'd like to code
it to read the size of a C# ushort, for example. The documentation says the
sizeof() is only supported in unsafe mode. Is there any equivalent to
sizeof() that I can use in managed code?

Aside from the other answers, you don't need to use sizeof to find the
size of a ushort - it's *always* 16 bits, just like an int is *always*
32 bits. The C# designers learned from the C experience that leaving
the sizes of primitive data types somewhat ambiguous is a bad idea :)

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
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