python: get the print output in an exec statement

Question

I want to get the output of an exec(...) Here is my code:

code = """
i = [0,1,2]
for j in i :
    print j
"""
result = exec(code)

How could I get the things that print outputed? How can I get something like:

0
1
2

Regards and thanks.

Answer 1

Since Python 3.4 there is a solution is the stdlib: https://docs.python.org/3/library/contextlib.html#contextlib.redirect_stdout

from io import StringIO from contextlib import redirect_stdout  f = StringIO() with redirect_stdout(f):     help(pow) s = f.getvalue() 

In older versions you can write a context manager to handle replacing stdout:

import sys from io import StringIO import contextlib  @contextlib.contextmanager def stdoutIO(stdout=None):     old = sys.stdout     if stdout is None:         stdout = StringIO()     sys.stdout = stdout     yield stdout     sys.stdout = old  code = """ i = [0,1,2] for j in i :     print j """ with stdoutIO() as s:     exec(code)  print("out:", s.getvalue()) 

Answer 2

Here is Py3-friendly version of @Jochen's answer. I also added try-except clause to recover in case of errors in the code.

import sys from io import StringIO import contextlib  @contextlib.contextmanager def stdoutIO(stdout=None):     old = sys.stdout     if stdout is None:         stdout = StringIO()     sys.stdout = stdout     yield stdout     sys.stdout = old  code = """ i = [0,1,2] for j in i :     print(j) """ with stdoutIO() as s:     try:         exec(code)     except:         print("Something wrong with the code") print("out:", s.getvalue()) 

Answer 3

You can redirect the standard output to a string for the duration of the exec call:

Python2

import sys
from cStringIO import StringIO

code = """
i = [0,1,2]
for j in i:
    print(j)
"""

old_stdout = sys.stdout
redirected_output = sys.stdout = StringIO()
exec(code)
sys.stdout = old_stdout

print(redirected_output.getvalue())

Python3

import sys
from io import StringIO

code = """
i = [0,1,2]
for j in i:
    print(j)
"""

old_stdout = sys.stdout
redirected_output = sys.stdout = StringIO()
exec(code)
sys.stdout = old_stdout

print(redirected_output.getvalue())