I am trying to make a C++ app, which returns a result to the C# app, which can be displayed, or maybe printed to the console.
For example, in my C++ file:
int main(int argc, char* argv[]){
// code
some_method_to_return_result("result");
}
And in my C# app
System.Diagnostics.Process.Start("exec.exe", "arguments");
some_method_to_get_result();
How would I be able to achieve this?
The best approach is to organize your C++ app as a dll and call this dll from the .NET process (C#). In this case you will have just one process. Calls from C# to C++ are very effective. Marshalling data in some cases can be tricky. In simple cases it is straightforward. Keep your data formats simple.
Prototype of your C++ function should look in C# like this:
[DllImport("avifil32.dll")]
private static extern void AVIFileInit();
Search for C# dllimport and C# extern for details.
I think you're slightly confused about what information is available when you spawn a process in C#. You can't just directly call a C++ method you need a bunch of ugly interop code that I don't know about. What you can get from your C++ app is main's return code (either 1 or 0). Something like the following will make it so result holds the return status of your C++ app after it's execution has completed.
Process P = System.Diagnostics.Process.Start("exec.exe", "arguments");
P.WaitForExit();
int result = P.ExitCode;
If you want to get other data from your C++ app you need to do some research on Marshalling which I'm not really knowledgeable on but I think this msdn article might be a good starting point; http://msdn.microsoft.com/en-us/library/eaw10et3(v=vs.110).aspx
In C++ write your result to standard output:
std::cout << "result";
In C# use Process.StandardOutput.ReadLine or similar way to grab the standard output of C++ application.
Maybe not the best solution, but probably the easiest would be to write to some file in your c++ code, and read from it in your c# code:
//c++
int main(int argc, char* argv[]){
ofstream fileToWrite;
fileToWrite.open ("file.txt");
fileToWrite << some_method_to_return_result("result");
fileToWrite.close();
}
//c#
string data;
using (StreamReader reader = new StreamReader("file.txt"))
{
data = reader.ReadLine();
}
Something like this?
using (Process p = new Process())
{
p.StartInfo.FileName = "filename.exe";
p.StartInfo.Arguments = "params";
p.StartInfo.UseShellExecute = false; // use CreateProcess
p.StartInfo.RedirectStandardOutput = true; // get stdout
p.StartInfo.RedirectStandardError = true; // get stderr
p.StartInfo.CreateNoWindow = true;
p.Start();
string line;
while (!p.StandardOutput.EndOfStream)
{
line = p.StandardOutput.ReadLine();
Console.WriteLine(line);
}
if (!p.StandardError.EndOfStream)
{
Console.WriteLine("Error: " + p.StandardError.ReadToEnd());
}
}
btw, this code was extracted from a real-world app which I wrote a long time ago.
