How can I run an external program from C and parse

Question

I've got a utility that outputs a list of files required by a game. How can I run that utility within a C program and grab its output so I can act on it within the same program?

UPDATE: Good call on the lack of information. The utility spits out a series of strings, and this is supposed to be complete portable across Mac/Windows/Linux. Please note, I'm looking for a programmatic way to execute the utility and retain its output (which goes to stdout).

Answer 1

For simple problems in Unix-ish environments try popen().

From the man page:

The popen() function opens a process by creating a pipe, forking and invoking the shell.

If you use the read mode this is exactly what you asked for. I don't know if it is implemented in Windows.

For more complicated problems you want to look up inter-process communication.

Answer 2

popen is supported on Windows, see here:

http://msdn.microsoft.com/en-us/library/96ayss4b.aspx

If you want it to be cross-platform, popen is the way to go.