Capture Return Value of python script invoked from C#

Question

I am trying to capture return (list) from python script below using C#. Stream reader gives me a null as a response. However, when I print the result I get the information in stream reader but when I use return(list) it does not.I have tried a lot of ways. Links and any info is appreciated. Python:

def main1():

    data1 =send_initdata("i", sock)

    list.append (send_data("a", sock,"1"))
    list.append (send_data("b", sock,"2"))

    #print (list)
    return (list)


if __name__ == '__main__':sys.exit(main1())

C#:

    void run_cmd()
    {


        ProcessStartInfo start = new ProcessStartInfo();
        start.FileName = @"C:\Python27\python.exe";
        start.Arguments = string.Format("{0} {1}", "Function.Py", "");
        start.UseShellExecute = false;
        start.RedirectStandardOutput = true;
        start.CreateNoWindow = true;


        using (Process process = Process.Start(start))
        {
            using (StreamReader reader = process.StandardOutput)
            {
                var result = reader.ReadLine();

            }
        }

Andrew Cooper · Accepted Answer · 2014-06-19 23:28:32Z

3

The return from a command-line process is always an integer, and is intended to indicate the presence or absence of errors during execution. You can't return a list as you're trying to do here.

Having the script print the list contents to STDOUT (as your commented print statement does), and then read that as your C# code does is the correct way to go. Alternately the script could write the list to a file and then your C# code read that file.

answered Jun 19, 2014 at 23:28

Andrew Cooper

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4 Comments

user2801184 Over a year ago

Thank you so much for the information Andrew! Now in C# if I use scope = engine.ExecuteFile( fileName); How can I use scope to run python file? Python file which has:if name == 'main':sys.exit(main1()) Appreciate your help!

Andrew Cooper Over a year ago

Sorry, I don't know much about the workings of Python, just command-line processes in general.

user2801184 Over a year ago

Thanks Andrew, By any chance you have any idea how can I capture single python function print command? var ipy = Python.CreateRuntime(options); dynamic Python_File = ipy.UseFile("Function.Py"); Python_File.main1();// how can I capture this output?

Andrew Cooper Over a year ago

I don't know what Python.CreateRuntime is. Is that Iron Python? It's possible that the API just sends the output of the python script directly to the STDOUT of your C# process.

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