PHP script and external C program

Problem. I have a php 4.0.6. on linux as Apache module. I need to do folowing: I have in my script some value, for example "$value" and in /bin on my linux box c language program called "something". (I need speed) . I need to parse $value thru stdin /bin/something program to get from its stdout a $parsed_value. How to run external program (for example /bin/something ), write to its STDIN $value and then read from its STDOUT to variable $parsed_value ? Example code needed. thanx