Getting output of a system command from stdout in C

I'm writing a C program under Android/Linux that runs a system command. The command outputs some text to stdout, and I'm trying to capture the output into a string or character array.

For example:

system("ls");

would list the contents of the current directory to stdout, and I would like to be able to capture that data into a variable programmatically in C.

How do I do this?

Thanks.