Capturing output with input

[gopala]

Hi, I am pretty new to python but i do have experience with c++. As a
part of learning exercise i wrote a python script to insert
beautifying comments(with name, problem...) to our lab program source
files (c language).

The script is working for most of the cases. The problem is i also
need to append the test output of the lab programs to the
corresponding source files(again the output should be added as a
beautified comment). The lab programs are interactive and very
different from each other. Currently in the script, i am prompting the
user(me!) to manually enter the output of the program which it to be
inserted. I want to eliminate this tedious step.

for eg i want "python commenter.py lab1.c" to initially prepend
comments with my name... and then spawn lab1.exe , capture its output
and append it with comments to lab1_com.c

My initial attempts of using spawn.. , exec.. pipe.. failed since they
can't capture the std input and std output continuously.
The lab1.exe will be something like

Enter 2 nos
2 3
The sum is 5

Now i should be able to capture all these.
Is this possible ? If so please do give me some hints on how to
achieve this.

Cheers,
Gopala Krishna