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Vb.net Cannot Be Marshaled As An Unmanaged Structure


David Jul 21 '05 #3 P: n/a David Browne Scratch that. THe orignal code is as follows: C#: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)] private struct FieldDescriptor { [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 11)] public string fieldName; public char fieldType; public Int32 address; What is a size of DateTime type in C#? - A trivial question, unexcitingly facing few obstacles. That implies the type for which the size is queried should be known at compile time. check over here

In such situations, Marshal.SizeOf method has to be used { class="code-keyword">int x = Marshal.SizeOf(typeof(LVITEM)); }, which returns the size of the structure depending on the StructLayoutAttribute applied. I'm using someone else's class: using HANDLE = System.IntPtr; namespace Win32 { // other stuff here public struct SHFILEINFO { public HANDLE hIcon; public int iIcon; public int dwAttributes; [MarshalAs(UnmanagedType.ByValArray, SizeConst=Kernel.MAX_PATH)] I see the SQL string (~1700 bytes) appear and then I receive the error message. InteropServices; public class Program { public static unsafe void Main (string [] args) { Console.

Cannot Be Marshaled As An Unmanaged Structure; No Meaningful Size Or Offset Can Be Computed.

There are two facilities in C# to determine the size of a type - sizeof operator andMarshal.SizeOf method. more hot questions question feed lang-vb about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation The struct is not a generic value type.sizeof should be imagined as a compile-time construct. The sizeof operator returns the size of the type in bytes as allocated by the CLR (on the current platform).

  1. Join them; it only takes a minute: Sign up VB.net Marshalling Error up vote 2 down vote favorite I have to create an array of structure type in VB.net.
  2. How to read a file that's in use by another process.
  3. Console:: WriteLine (string, object) L_0011: nop L_0012: ldstr "DateTime size: {0}" L_0017: sizeof [mscorlib] System.

WriteLine ("DateTime size: {0}", sizeof (DateTime)); L_0000: nop L_0001: ldstr "Int size: {0}" L_0006: ldc.i4.4//sizeof (int) - a constant L_0007: box int32 L_000c: call void [mscorlib] System. But ideally it does not sound convincing to me because the compiler uses the MSIL sizeof instruction to computer the size, instead of hard coding the size (as is done for Value Types: User-defined value (and reference types) are composed of the primitive value types exposed by the compiler, most of which exist as keywords – int, bool, char, long, double etc. I don't understand the marshalling very well, so this is kind of stumping me.

sizeof operator and Marshal.SizeOf method. Vb.net Sizeof MFC - Part I Window Tabs (WndTabs) Add-In for DevStudio SAPrefs - Netscape-like Preferences Dialog AngleSharp Comments and Discussions You must Sign In to use this message board. Got any clue? Consider a class (reference type) SomeClass containing a char and a string.

I used the following method to marshal it in VB.net Public Structure grpr_output_block1 Public drg As drg_grpr_block1 End Structure Using in code - to pass as pointer in function To start viewing messages, select the forum that you want to visit from the selection below. WriteLine (Marshal. Otherwise, it can be used with primitive or user-defined value types.

Vb.net Sizeof

It's quick & easy. What is a size of DateTime type in C#? Cannot Be Marshaled As An Unmanaged Structure; No Meaningful Size Or Offset Can Be Computed. I'm having a problem that I don't quite understand. C# Marshal Sizeof DateTime//sizeof (DateTime) L_001d: box int32 L_0022: call void [mscorlib] System.

When we say sizeof(GenValueType), the (closed) type definition GenValueType is not available at compile time but only at runtime. Login using Answers In Focus DOWNLOAD: C# Corner Android App Version 0.5.4 Why Developers Should Focus On Communication LEARN: How to become a Microsoft MVP C# Corner Annual This is easiest to do as a two step rocket. DateTime ' cannot be marshaled as an unmanaged structure; no meaningful size or offset can be computed.at System.Runtime.InteropServices.Marshal.SizeOf (Type t)at Program. C# Sizeof

Unlike sizeof (C# keyword), this one is offered from the BCL. Reply With Quote Quick Navigation C-Sharp Programming Top Site Areas Settings Private Messages Subscriptions Who's Online Search Forums Forums Home Forums Visual C++ & C++ Programming Visual C++ Programming Visual C++ SizeOf Hello, AlexZu, you wrote:AZ> The matter is that DateTime it is marked by attribute StructLayout with type of alignment LayoutKind. Refer MSDN for the sizes of primitive types.

However, the sizeof cannot be freely used with user-defined value types (struct) but only if the following conditions are true:- The size of the struct is requested from within an Reference types are basically (C++) pointer like. SizeOf Programmer's Town ».NET »Problems with Marshal.

WriteLine (sizeof (DateTime));//8 Console.

com... Edited by Mudoch2505 Tuesday, October 18, 2011 8:56 PM Tuesday, October 18, 2011 8:49 PM Reply | Quote Answers 0 Sign in to vote Works fine in VB2008E with continuation characters: Also, every .NET object incurs a 16 (I guess) byte header overhead. C# - the fastest way to iterate over dictionary Having a big dictionary, say 1M of samples - what is the fastest way to iterate over it?

SizeOf Hello, nikov, you wrote:N> At attempt to define the size occupied with structure DateTime, ran into an exception:N> Thus in a kompajl-time the operator sizeof works normally. Does that mean we don't need to compute the size of a type at all when working in the CLR world? But the size of an instance of the same closed type may be determined. ByValArray can only be used with arrays.

Post your question and get tips & solutions from a community of 418,795 IT Pros & Developers. Consider the following ... DFB vs. And the error makes sense - Type cannot be marshaled as an unmanaged structure; no meaningful size or offset can be computed.

418,795 Members | 1,052 Online Join Now login Ask Question Home Questions Articles Browse Topics Latest Top Members FAQ home > topics > .net framework > questions > type Mattias -- Mattias Sjgren [MVP] mattias @ mvps.org http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com Please reply only to the newsgroup. Results 1 to 3 of 3 Thread: [RESOLVED] Error marshalling pointer to struct with char[] Tweet Thread Tools Show Printable Version Email this Page… Subscribe to this Thread… Display Linear Mode As a side note; since you in your structure have specified the fixed size for each of the fields, you don't need to pad the values with spaces in your code;

asked 7 years ago viewed 3087 times active 6 years ago Upcoming Events 2016 Community Moderator Election ends Nov 22 Linked 0 Object Array to Byte Array - Marshal.AllocHGlobal Fragmentation query Should we consider the header size too and the same question applies here too - 16 bytes or the mazy data structure that the header actually refers to. Within the managed application, size does not matter; since there are types provided by the CLR for creating\managing fixed size and variable size (typed) arrays. Also you can always marshal it as a big byte array and sort it out after the fact.

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