Call external program from python and get its output

Question

I want to call a program (.exe), which is written in C++ and compiled, from Python. The executable takes as input two files and returns a score.

I need to do this for multiple files. So, I would like to write a small script in python which loops over multiple files, passes them to the executable and gets back the values.

Now, I have done my search and I know about SWIG and Boost::Python may be an option but I was trying to find if there is an easier way. I do not need to 'extend' the C++ program. I simply want to call it just like I would from a command line and get the returned number.

Answer 1

To run an external program and get its output, use subprocess.check_output on Python 2.7+. The example from the docs:

>>> subprocess.check_output(["ls", "-l", "/dev/null"])
'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'

check_call just returns the return code of the program, not the output.

Answer 2

You can use the subprocess module for that.

result = subprocess.check_output(['your_program.exe', 'arg1', 'arg2'])