C# – way to call an unmanaged (not COM) dll from C# application

cinteropmarshallingunmanaged

Is there a way to use (reference) a DLL written in an unmanaged C++ (not a COM library) in my C# application?

When I try to reference it from within Visual Studio, I get 'not a COM object' error message.

Maybe there is some kind of translator\router that would COMify my DLL reference?
I have no clue how COM and COM interop work, since I started programming when this was already unnecessary for me.

Thank you.

Best Answer

You need to use the DllImport attribute. Here's an example for the Win32 PostMessage function:

[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool PostMessage(IntPtr handle, int message, IntPtr wparam, IntPtr lparam);

Related Solutions

Ruby – How to call shell commands from Ruby

This explanation is based on a commented Ruby script from a friend of mine. If you want to improve the script, feel free to update it at the link.

First, note that when Ruby calls out to a shell, it typically calls /bin/sh, not Bash. Some Bash syntax is not supported by /bin/sh on all systems.

Here are ways to execute a shell script:

cmd = "echo 'hi'" # Sample string that can be used

Kernel#` , commonly called backticks – `cmd`

This is like many other languages, including Bash, PHP, and Perl.

Returns the result (i.e. standard output) of the shell command.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-60
```
value = `echo 'hi'`
value = `#{cmd}`
```
Built-in syntax, %x( cmd )

Following the x character is a delimiter, which can be any character. If the delimiter is one of the characters (, [, {, or <, the literal consists of the characters up to the matching closing delimiter, taking account of nested delimiter pairs. For all other delimiters, the literal comprises the characters up to the next occurrence of the delimiter character. String interpolation #{ ... } is allowed.

Returns the result (i.e. standard output) of the shell command, just like the backticks.

Docs: https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-Percent+Strings
```
value = %x( echo 'hi' )
value = %x[ #{cmd} ]
```
Kernel#system

Executes the given command in a subshell.

Returns true if the command was found and run successfully, false otherwise.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-system
```
wasGood = system( "echo 'hi'" )
wasGood = system( cmd )
```
Kernel#exec

Replaces the current process by running the given external command.

Returns none, the current process is replaced and never continues.

Docs: http://ruby-doc.org/core/Kernel.html#method-i-exec
```
exec( "echo 'hi'" )
exec( cmd ) # Note: this will never be reached because of the line above
```

Here's some extra advice: $?, which is the same as $CHILD_STATUS, accesses the status of the last system executed command if you use the backticks, system() or %x{}. You can then access the exitstatus and pid properties:

$?.exitstatus

For more reading see:

R – Class Not Registered…. when trying to call a managed C# library from unmanaged C++

A better way of using unmanaged objects in managed code is to use C++ / CLI. You can easily create a managed wrapper around the native object.

Best Answer

Related Solutions

Ruby – How to call shell commands from Ruby

R – Class Not Registered…. when trying to call a managed C# library from unmanaged C++

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