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I am getting C++ compilation issues while compiling my project

I am trying to implement the zoom sdk and want to prevent my screen to be captured and by screen shots for this purpose they have given some functions to be placed inside the project. When I place the code inside the function I start getting some errors and when I remove then the errors are gone.
The code which need to be placed inside the project is as follows:
BOOL CALLBACK EnumWindowsCB(HWND hwnd, LPARAM lParam)
{
SetWindowDisplayAffinity(hwnd, WDA_MONITOR);
return TRUE;
}
void CZoomSDKeDotNetWrap::DisableScreenRecord() {
DWORD pid = GetCurrentProcessId();
EnumWindows(EnumWindowsCB, pid);
uint8_t* func_data = (uint8_t*)GetProcAddress(GetModuleHandle(L"user32.dll"), "SetWindowDisplayAffinity");
}
Please let me know what these errors mean and how to resolve them.
The errors are:
enter image description here

You need to add a reference to the respective library(dll) you're using in the function you're trying to put inside the library.
As seen in your code above you're trying to use standard Windows libraries. Have you tried editing your project properties then linker input options to include user32.lib?

Thank you everyone who answered. Actually it was just because I was not using user32.lib library in the project when I added the errors got removed and it started working for me.

To share an exported C++ DLL event, within an external C++ Win32 Application

Have a good day!
For portability reasons, i have created a C++ DLL with almost novice C++ knowledge just by searching thousands of pages, hundreds of compiling error corrections and couple of stackoverflow questions.
It is far beyond being stable but it is working most of the time :)
Just for curiosity and modularity reasons without importing the header and the cpp file to my application, i would like to ask your advice and help:
C++ Win32 Console Application
int main()
{
HMODULE lib = LoadLibrary(L"Serial.dll");
typedef void(*void_Connect)(UINT Port, UINT Baud);
void_Connect Connect = (void_Connect)GetProcAddress(lib, "Connect");
Connect(1, 9600);
}
I want to add an event into above C++ Win32 Console application, which will be triggered or hosted by the DLL
For example, a Received_Event(const char* data) or Connected_Event(BOOL status) with parameters.
Part from the DLL
typedef void(*fpCALLBACK) (const char* aParam);
static fpCALLBACK s_pCallback = NULL;
extern "C"
{
#define DLL __declspec(dllexport)
DLL void ReceivedEventRegister(fpCALLBACK p_pCallback)
{
s_pCallback = p_pCallback;
}
DLL void evntReceived(const char *receivedData);
}
DLL void evntReceived(const char *received)
{
s_pCallback(received);
}
I want to achive something similar to this C# version, with Standard C++
private static ManagedCallbackDelegate MessageCallbackDelegate;
public delegate void ManagedCallbackDelegate(string aParam);
[DllImport("Serial.dll", EntryPoint = "ReceivedEventRegister", CallingConvention = CallingConvention.Cdecl)]
private static extern void ReceivedEventRegister(ManagedCallbackDelegate callback);
static private void serialRecieved(string data)
{
Console.WriteLine(data);
}
static void Main(string[] args)
{
MessageCallbackDelegate = new ManagedCallbackDelegate(serialRecieved);
ReceivedEventRegister(MessageCallbackDelegate);
}
With C# code above, any data received by the DLL, the serialRecieved function is called in realtime. I want to achive this with Standard C++
I want to be informed or be aware of with the DLL process in realtime, in my Win32 C++ Console Application. ( Without blocking the Win32 Console application )
No MFC. if it is possible, no Component Object Model (It is possible with C# without need to convert the DLL into a COM). if it is possible, I want to do it with Standard C++.
I am compiling things with Visual Studio 2017 Community
Please go easy with me. It is a hobby for me and i just do it in my spare time.
Questions
Can you reference me some code examples written for this purpose, you are aware of?
Is there any specific name for this kind of communication that i can Google?
Is there any approach, you can suggest?
Thank you!

Once again, thanks to #dxiv's comment; helped me a lot, to sort things out! Even, when someone tells you that it should work, you resolve 90% of the problem.
At the DLL side
DLL void evntReceived(const char *received)
{
s_pCallback(received);
}
The DLL is calling the above function all the time as soon as it receives any data. To get that data realtime in your Win32 C++ Application, you need to import the DLL function which is calling the above callback function. Which is this
DLL void ReceivedEventRegister(fpCALLBACK p_pCallback)
part of the DLL.
As the DLL function's parameter type name fpCALLBACK suggests, our function parameter has to be as it is defind in the DLL:
typedef void(*fpCALLBACK) (const char* aParam);
At the Application side
//Callback Function: A function that is passed to another function as an argument
void Event_Received(const char *recvd)
{
std::cout << recvd << std::endl;
}
int main()
{
HMODULE lib = LoadLibrary(L"Serial.dll");
typedef void(*void_Connect)(UINT Port, UINT Baud);
void_Connect Connect = (void_Connect)GetProcAddress(lib, "Connect");
// Type definition of the function pointer.
// In our case: a Void type, which takes in a
// void type function pointer with a parameter (const char *aParam)
// dllCALLBACK is just a type name; you can name it whatever you want.
typedef void(*dllCALLBACK) (void(*fpCALLBACK) (const char* aParam));
// Now we will import the function from our DLL which takes
// the same parameters as we defined above, to call
// our callback function
dllCALLBACK ReceivedEventRegister = (dllCALLBACK)GetProcAddress(lib, "ReceivedEventRegister");
// Call the callback function with the imported function above.
// And that is all there is to it. As soon as any data received
// by our DLL - our Event_Received callback function
// fires in our C++ Win32 Console Application
ReceivedEventRegister(Event_Received);
Connect(1, 9600);
}
If you are a novice like me this video may help you to understand about Callback functions.
Thank you #dxiv again, taking time to read and answer my question!

Go to library to C# | BadImageFormatException

I would like to create a library out of go-code and use it inside a C# winforms project.
For the error scroll to the bottom.
Setup
GO 1.10.2
tdm-gcc-5.1.0-3
Windows 10 / x64
Go-project called exprt
What I've tried
I've created a minimal go-tool that creates a file in the working-dir:
package main
import (
"os"
"C"
)
func main() {
// nothing here
}
//export Test
func Test() {
os.OpenFile("created_file.txt", os.O_RDONLY|os.O_CREATE, 0666);
}
The next steps were taken from Building a dll with Go 1.7.
I've then compiled to c-archive with the following command: go build -buildmode=c-archive which gives me exprt.a and exprt.h.
After that I've created a file called goDLL.c (1:1 as in the link above) and inserted this code:
#include <stdio.h>
#include "exprt.h"
// force gcc to link in go runtime (may be a better solution than this)
void dummy() {
Test();
}
int main() {
}
Lastly I've run this command to create my final dll:
gcc -shared -pthread -o goDLL.dll goDLL.c exprt.a -lWinMM -lntdll -lWS2_32
which gave me "goDLL.dll".
My problem
In C# I've created a winforms-project with 1 button that calls this declared function (copied the dll to the debug-folder):
[DllImport("goDLL.dll")]
private static extern void Test();
Error
System.BadImageFormatException: "An attempt was made to load a program with an incorrect format. (HRESULT: 0x8007000B)"
Sorry for that big block of text but this was the most minimal test I could think off.
I appreciate every help in here.

Well, in the given answer here https://social.msdn.microsoft.com/Forums/vstudio/en-US/ee3df896-1d33-451b-a8a3-716294b44b2b/socket-programming-on-64bit-machine?forum=vclanguage there is written:
The implementation is in a file called ws2_32.dll and there are 32-bit and 64-bit versions of the DLL in 64-bit Windows.
So the build as described in my question is correct.
Solution
The C#-Project has to be explicitly set to x64. AnyCPU won't work and throw the error shown in the question above.
Everything is working now. I'm leaving the question and answer as this is a full explanation of how to get go-code running out of C#.

Creating a CPP DLL for use in a C# program

So I have a WPF solution. I added a new project and added a CPP Dll project to it.
I used this example. Pretty straight forward.
http://www.codeproject.com/Articles/9826/How-to-create-a-DLL-library-in-C-and-then-use-it-w
Here is my code
CppTestDll.cpp
#include <stdio.h>
extern "C"
{
__declspec(dllexport) void DisplayHelloFromDLL()
{
printf("Hello from DLL !\n");
}
}
When I build this I do in fact get a DLL
Now when I go into my WPF app and attempt to add a reference to this DLL I get this error.
"A reference to 'C:\DIR\testcppdll.dll' could not be added. Please
make sure that the file is accessible, and that it is a valid assembly
or COM component."

If you look in the example you cite:
Creating a simple C# application:
Start Visual Studio .NET. Go to File->New->Project.
Select Visual C#
Project. ... (you can select WPF Project)
Give the name to your application. Press OK. Into the specified
class, insert the following two lines:
[DllImport("TestLib.dll")]
public static extern void DisplayHelloFromDLL ();
In C#, keyword extern indicates that the method is implemented externally.
Your code should look something like this:
using System;
using System.Runtime.InteropServices; // DLL support
class HelloWorld
{
[DllImport("TestLib.dll")]
public static extern void DisplayHelloFromDLL ();
public void SomeFunction()
{
Console.WriteLine ("This is C# program");
DisplayHelloFromDLL ();
}
}
You don't add a reference to the to the DLL - you P/Invoke the Function using DLLImport

pinvoke return a float

have been working on this for hours, couldn't get it work :(
below code gives exception "Attempted to read or write protected memory. This is often an indication that other memory is corrupt." this is fixed, see below update
but when i change the return type to int and return a int value, it works. how to make it to return a float value? thanks.
vs2012
c++ code
extern "C" __declspec(dllexport)
float compute_similarity()
{
return 1.01;
}
c# code
[DllImport("demo.exe", EntryPoint = "compute_similarity", CallingConvention = CallingConvention.Cdecl)]
public static extern float compute_similarity();
public void Get()
{
float x = compute_similarity(); // here returns random value
}
=====================================
UPDATE
See comments from David below, the problem was the c# project is targeting x64 and c++ is targeting Win32. After changing the c# project to target to x86, the exception went away.
However the call from c# returns some random value instead of 1.01 expected

I think your problem is that your function is declared in an executable rather than a DLL. Convert your native code into a library project and compile a DLL.
Your code will result in a call to LoadLibrary passing the file name demo.exe. The documentation for LoadLibrary says:
LoadLibrary can also be used to load other executable modules. For example, the function can specify an .exe file to get a handle that can be used in FindResource or LoadResource. However, do not use LoadLibrary to run an .exe file. Instead, use the CreateProcess function.
And so your code is doing exactly what you are told not to do. The call to LoadLibrary will succeed. The subsequent calls to GetProcAddress will succeed. But the module that you loaded is not fit to execute code.