In python, how to capture the stdout from a c++ shared library to a variable

Question

For some other reasons, the c++ shared library I used outputs some texts to standard output. In python, I want to capture the output and save to a variable.

Answer 1

For anyone who came here from google to find how to suppress stderr/stdout output from shared library (dll), just as me, I post next simple context manager based on Adam's answer:

class SuppressStream(object): 

    def __init__(self, stream=sys.stderr):
        self.orig_stream_fileno = stream.fileno()

    def __enter__(self):
        self.orig_stream_dup = os.dup(self.orig_stream_fileno)
        self.devnull = open(os.devnull, 'w')
        os.dup2(self.devnull.fileno(), self.orig_stream_fileno)

    def __exit__(self, type, value, traceback):
        os.close(self.orig_stream_fileno)
        os.dup2(self.orig_stream_dup, self.orig_stream_fileno)
        os.close(self.orig_stream_dup)
        self.devnull.close()

Usage (adapted Adam's example):

import ctypes
import sys
print('Start')

liba = ctypes.cdll.LoadLibrary('libtest.so')

with SuppressStream(sys.stdout):
    liba.hello()  # Call into the shared library

print('End')