I'm trying to redirect the output of printf functions to a file on Windows. I'm using ctypes with python3 to invoke the functions. My code is:

import os, sys
from ctypes import *

if __name__ == '__main__':

 print("begin")
 saved_stdout=os.dup(1)
 test_file=open("TEST.TXT", "w")
 os.dup2(test_file.fileno(), 1)
 test_file.close()
 print("python print")
 cdll.msvcrt.printf(b"Printf function 1\n")
 cdll.msvcrt.printf(b"Printf function 2\n")
 cdll.msvcrt.printf(b"Printf function 3\n")
 os.dup2(saved_stdout, 1)
 print("end")

But when I run the code from Eclipse I get the following on the screen:

begin
end
Printf function 1
Printf function 2
Printf function 3

...and the following in the TEST.txt

python print

When I run this from cmd, this is what is on the screen:

begin
end

..and this is in the TEST.txt:

python print

When I comment out the second dup2() statement e.g.

import os, sys
from ctypes import *
if __name__ == '__main__':

    print("begin")
    saved_stdout=os.dup(1)
    test_file=open("TEST.TXT", "w")
    os.dup2(test_file.fileno(), 1)
    test_file.close()
    print("python print")
    cdll.msvcrt.printf(b"Printf function 1\n")
    cdll.msvcrt.printf(b"Printf function 2\n")
    cdll.msvcrt.printf(b"Printf function 3\n")
    #os.dup2(saved_stdout, 1)
    print("end")

From Eclipse, on the screen:

begin

...and in the TEST.txt file:

python print
end
Printf function 1
Printf function 2
Printf function 3

From cmd, on the screen:

                        
                        python
                        
                        windows
                        
                        ctypes
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