I have a Delphi DLL with a function defined as:
function SubmitJobStringList(joblist: tStringList; var jobno: Integer): Integer;
I am calling this from C#. How do I declare the first parameter as a tStringList does not exist in C#. I currently have the declaration as:
[DllImport("opt7bja.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
public static extern int SubmitJobStringList(string[] tStringList, ref int jobno);
But when I call it I get a memory access violation exception.
Anyone know how to pass to a tStringList correctly from C#?
You'll most likely not have any luck with this. The TStringList is more than just an array, it's a full-blown class, and the exact implementation details may differ from what is possible with .NET. Take a look at the Delphi VCL source code (that is, if you have it) and try to find out if you can rebuild the class in C#, and pass it with the help of your best friend, the Interop Marshaller. Note that even the Delphi string type is different from the .NET string type, and passing it without telling the marshaller what he should do, he will pass it as a char-array, most likely.
Other than that, I would suggest changing the Delphi DLL. It's never a good thing to expose anything Delphi-specific in a DLL that is to be used by non-Delphi clients. Make the parameter an array of PChar and you should be fine.
If this is your DLL, I'd rewrite the function to accept an array of strings instead. Avoid passing classes as DLL parameters.
Or, if you really want to use a TStringList for some reason, Delphi's VCL.Net can be used from any .Net language.
An old example using TIniFile: http://cc.codegear.com/Item/22691
The example uses .Net 1.1 in Delphi 2005. Delphi 2006 and 2007 support .Net 2.0.
If you don't control the DLL and they can't or won't change it, you could always write your own Delphi wrapper in a separate DLL with parameters that are more cross-language friendly.
Having a class as a parameter of a DLL function really is bad form.
I am not exactly clear your way of using delphi and C#. It seems you have created a Win32 DLL which you want to call from C#. Offcourse you must be using PInvoke for this.
I would suggest that you create a .NET DLL using your source code since complete porting of VCL is available. I can further elaborate if you wish....
In theory, you could do something like this by using pointers (casting them as the C# IntPtr type) instead of strongly typed object references (or perhaps wrapping them in some other type to avoid having to declare unsafe blocks), but the essential catch is this: The Delphi runtime must be the mechanism for allocating and deallocating memory for the objects. To that end, you must declare functions in your Delphi-compiled DLL which invoke the constructors and destructors for the TStringList class, you must make sure that your Delphi DLL uses the ShareMem unit, and you must take responsibility for incrementing and decrementing the reference count for your Delphi AnsiStrings before they leave the DLL and after they enter it, preferably also as functions exported from your Delphi DLL.
In short, it's a lot of work since you must juggle two memory managers in the same process (the .NET CLR and Delphi's allocators) and you must both manage the memory manually and "fool" the Delphi memory manager and runtime. Is there a particular reason you are bound to this setup? Could you describe the problem you are trying to solve at a higher level?
As Hemant Jangid said, you should easily be able to do this by compiling your code as a .NET dll and then referring to that assembly in your c# project.
Of course, you'll only be able to do this if the version of Delphi you have has Delphi.NET.
I don't know a lot about c#, but a technique that I use for transporting stringlists across contexts is using the .text property to get a string representing the list, then assigning that property on "the other side".
It's usually easier to get a string over the wall that it is a full blown object.
Related
I've been working recently in COM interop thing.Read some Good books about it C++/CLI in Action By Nishant Shivakumar. I also went through this link by Srinivas wherein he has explained beautifully how to Consume C# libraryin native C++ using C++/CLI.I downloaded the code present at the bottom of the page..Read it..And loved it.My application is loosely based on it. I have a question though in that example(which you can download it there).
In C# Library "Worker.cs",If I have a method in the Worker class with a signature like this::
public void GetStudent(ManagedStudent student,int ){....}
FYI:: I need the object parameter because I would be accessing a method from that class in the Worker Class.
In C++/CLI wrapper project, NativeInterface.h, I wanted to export a method which gets this managed object as a parameter unlike the example.
__declspec dllexport void GetStudent(ManagedStudent^ obj)
What is the equivalent of an object in C++/CLI?
And later I want to access this method by importing this method by passing an object in my native Win32 Application/DLL.
I am including the "NativeInterface.h" file in my native dll/App . But an error comes while building the dll/App..managed targeted code requires \clr option.
FYI::
1. My WIN32 dll/app is being compiled with no \clr support and my wrapper with \clr support
2. I believe the error comes because of the handle used as a parameter? I want to access UnmanagedStudent(Object obj) in native app/dll;
Is that possible
It's possible, but you can't pass a .NET object to a native DLL, which is a native C++ code...
The equivalent of an .NET object in native C++ is C++ object... but this is like asking a C# to understand Native or PHP, or....
So, there are several approaches.
Don't use C++ managed wrapper. Instead using Marsahling and C# interoperability directly call into native C++, in 1 of 2 ways:
Pass the object fields as a long list of parameters to the C++ and re-construct the object inside native C++. A bit "not nice" approach but very efficient and easy to debug.
You can also pass the object as a class pointer to the C++ native directly, you need first to create the right marshaling in C#. See here:
http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.marshal(v=vs.110).aspx
Use C++ Interop (which you are doing...). You need to compile with Mixed mode! See this nice example:
http://social.msdn.microsoft.com/Forums/en-US/vclanguage/thread/f2de75c5-50a6-41ac-9ddf-694a8c0ce75b/
BUT... you need to understand the basics and know how to compile it:
http://msdn.microsoft.com/en-us/library/x0w2664k.aspx
Interoperability is a complex issue... and I try to write a short answer, please revert to me for further clarifications....
I am attempting to write a C# class (2010) that allows the usage of functions contained in a legacy C++ dll. The functions are exported using __stdcall, and have varying sets of parameters. I have no issue dealing with strings and other primatives, and am able to invoke these functions without issue.
The problem is that a few of the functions contain a CArray & reference as a parameter. I cannot figure out how to marshal this datatype, or if it's even possible.
I can't change the legacy DLL code, unfortunately.
To deal with this correctly, you can make a wrapper DLL (using the same MFC/C++ runtime version as what you want to call into, and make sure accepts the same array in the form of, say, a traditional pointer to a native C++ array.
This wrapper DLL can be called into from C#.
You could try with a more recent MFC version (and use C++/CLI for the marshalling), but then the new CArray could be binary incompatible with what to legacy library expects.
I wrote my program in C++ and exported it as a DLL. I have a C# WPF GUI and I want to import the DLL to do the processing.
I am very new to C#. How can I use the C++ class in C#? I know I can't just use the .h file.
Because I used pointers in C++, in C# I couldn't use pointers. That's why I got confused. Like in C++ i used char* instead of string, and I need to return double* for a big collection of double data, and things like that.
There are a number of ways:
Export the DLL functions and use DllImportAttribute to P/Invoke into the DLL.
If it is a COM DLL, then you can generate a Runtime Callable Wrapper via TLBIMP.exe
You can use C++/CLI to build create a .Net assembly which loads and calls methods on the DLL natively.
To address your additional concerns, yes, you can use pointers in C#. If you have a function which has a double* parameter, you can declare that in C# like this:
[DllImport("Your.DLL")]
private static extern unsafe void DoProcessing(double* data, int dataSize);
You need to make sure you check the "Allow Unsafe Code" checkbox on the build tab of the C# project, and after that, you can use pointers to your heart's content.
However, note that while I'm providing the pointer signature here, since you are obviously comfortable with pointers, there are other signatures which could be more safe for you to use, and would not require you to compile C# with unsafe code. The standard marshaller in the CLR will take care of the conversion from a pointer to a C# array, provided you give it a bit of a hint if the length is required:
[DllImport("Your.DLL")]
private static extern void DoProcessing(
[MarshalAs(UnmanagedType.LPArray, SizeParamIndex=1)] double[] data,
int dataSize);
This instructs the marshaller to use the parameter at index 1 (the 2nd parameter) as the size of the array of doubles pointed at by the 1st parameter. This allows you to avoid pointers in C#, and use safe CLI types. However, if you like pointers, my advice is to just use them - the C# will be easier for you than having to figure out how to write the method signature without them.
For more details on P/Invoke, refer to this documentation: http://msdn.microsoft.com/en-us/library/aa288468(VS.71).aspx
A lot depends on the structure of your C++ dll. If you have just a handful of functions, and they are not member functions of a class, then you can make them "extern C" functions and use the P/Invoke capability in .NET (sometimes called DllImport because of the attribute you use) to access the functions from C#.
I have win32 DLL named VssSdkd.dll. It contains two classes with names VssSdkServiceLogin and VssSdkMsg.
I need to import the VssDskServiceLogin class, in C#. I am setting few properties of VssDskServiceLogin object and passing this to VssSdkMsg which in turn invokes some other method.
How can I achieve this using C#.
I have win32 DLL named VssSdkd.dll. It
contains two classes with names
VssSdkServiceLogin and VssSdkMsg.
In C#, I need to import the
VssDskServiceLogin class. In the class
are some attributes I need to set the
value for, sending the information to
VssSdkMsg and call another function
I need to achieve those things through
C# code. Is this possible, and if so,
how?
Classes compiled in C++ (and other Win32 languages) cannot be interoped with Dot NET languages. Structures may be if care is taken. Dot NET does have support for COM objects, though.
Native functions may be called from Dot NET languages if they're tagged with the [DllImport] attribute on the CLR side (and the appropriate DllImportAttribute properties are set) - and exported on the Win32 side. However, this is a non-trivial process. I would recommend grabbing a good book on the subject and starting from the top. SO is probably not a very good medium for addressing this issue.
You can do it with p/invoke and marshaling. Read about it, it's too complicated a subject to explain fully in a SO answer.
I believe it is sometimes possible in C# through P/Invoke, but when dealing with classes, this can get very, very difficult.
I'd highly recommend creating a C# wrapper for your DLL using Managed C++ instead.
I don't know that this link will solve your problem directly, but I expect you can find a good example of how to do this at Code Project. Managed C++ can be a little tricky until you get used to it, and I think the syntax changed from .NET 1.0/1.1 to .NET 2.0. Make sure you know what version of .NET you're targeting and search the Code Project site accordingly.
Possibly what you are looking for is interoperability with COM.
I haven't worked much on it, but can give you a sample code to start with.
[DllImport("user32.dll")]
private static extern int MessageBox(IntPtr hWnd, String
text, String caption, uint type);
static void Main(string[] args)
{
MessageBox(new IntPtr(0), "Hello, world!", "My box", 0);
}
This may be of help.
I want to transfer a structure of data to an application which is created in C#.
I will be filling the structure in a VC++ program.
How can I send it?
Is structure suppported in C#?
Or else if I use LPDATA in VC++: how can I get the same thing in C#?
Defining the struct in C#
When defining your struct in C# make sure you use datatypes which match the C++ implementations. Char in C++ as Byte in C# etc...
You need to add some attributes to ensure your struct memory layout in C# matches the C++ implementation
[StructLayout(LayoutKind.Sequential, Size=TotalBytesInStruct),Serializable]
public struct MyStruct
{
}
Passing the struct
Declare a struct in C# using the same data structure. Pass a pointer to the struct to your C# app from C++ and cast it to the new struct in C#.
Calling you C# dll
For calling your C# DLL, your best option is to use a mixed mode assembly in C++. This allows you to use the pragmas managed and unmanaged to switch between native and managed code. This way you can nicely wrap you C# class with a workable C++ wrapper. See this Microsoft article. Be aware though, this is not supported on Mono.
Yes, structure is supported and can be used. Strings may require a bit of work, however.
Show us your structure. C# has marshaller helpers to map its types to native c++ types easily, you just have to know how to decorate your types, and we can help with that if you show us your structure.
For example, that LPDATA thing you mentioned, if that's char *, it maps directly over byte[] in C# if it's a generic buffer, or string if it's a normal string (the string mapping requires marshaller help, but it's a lot easier to use once decorated properly).
You could learn a lot from the "platform invoke tutorial" on MSDN.
The only difference is that you'll be invoking your own DLL :)