Call Script From C++

[ricomoss]

I have a Python script that I've made to convert the output file of a C++ program. I'd like to have C++ call the script but can't seem to find a good way to do this.

I'm not trying to embed or extend Python code in C++. I just want to be able to call the Python script from within C++ and pass it arguments.

For example:

int main()
{
    string filename;
    doesSomethingCool();
    writesFile(filename);

    // Call the Python script passing a filename argument.
    niftyPythonScript(filenameToConvert);
}

Obviously this code won't work...it's just an example of what I'm hoping to do. Is there a way to call niftyPythonScript.py with the argument filenameToConvert?

What if the location of the script is in an arbitrary location (but still known). Suppose it's always in /vol/data/files/niftyPythonScript.py...

[ricomoss]

I think I've made progress on this. If I want to call a script from C++ I can do the following.

Using the example above:

int main()
{
    string filename;
    doesSomethingCool();
    writesFile(filename);

    // Call the Python script passing a filename argument.
    std::string command = "./niftyPythonScript.py ";
    command += filename;
    system(command.c_str());
}

[Lv0f92yv]

Thanks to SteakRider from another post for this:
Edit: http://www.cplusplus.com/forum/windows/1341/ - SteakRider's post about windows system commands.

command += " file1.txt";

As if you were running from the terminal and executing your script from there, should work.

Then it will look like:

system( "./pythonscript file1.txt" );

[ricomoss]

As a follow up to this problem:

Suppose I know that the Python scripts are in the same directory as the C++ file.

Example:

Assume myCode and niftyPythonScript.py are both contained in /home/username/someDirectory/anotherDirectory/. I'd like the following two commands to work the same.

Command 1:

username@computer:~$ ./someDirectory/anotherDirectory/myCode

Command 2:

username@computer:~/someDirectory/anotherDirectory$ ./myCode

Where myCode is the executable from the C++ code that calls niftyPythonScript.py.

How can I construct command so that it will search the same relative path of the C++ file no matter where the user runs the C++ code from.

[Lv0f92yv]

I think the ./scriptname is relative to the C++ executable that uses it. It should be relative by default, regardless of where you execute the C++ program from, as long as the C++ program is in the right place.

In short: Those two commands should do the same thing. If they don't then I am confused.

[sohguanh]

system command only works if your C++ program don't intend to receive any input based on the Python script output.

That is, Python script will output 1,2,3 and this is needed as input by C++ program. To enable that, you may want to consider fork (expensive), pipe, socket, msg etc API calls instead. (I assume you using Linux environment).