Testing as you code on large C projects

I've been having a look over the PHP-SRC project, and I've read over the brief development guide at: http://ift.tt/1KP49Pz

However being relatively new to C (but not new to programming), I am a little taken aback by the thought that I need to recompile every time I need to test a change.

When writing in PHP, I can bolt on a small snippet to see if x == y at a certain point of execution and test it almost immediately. But before I start diving in a project as large as PHP, I want to know if I am mistaken in that I would need to build the entirety of the source to test small changes.

Is there a stage in the build process where small changes can be compiled into an existing binary without waiting 10-20 minutes every time?