title: How do you configure GCC in Eclipse to use C99?
body: <p>I'm working on a small C project in Eclipse; I just installed Eclipse from the Ubuntu Software Center and added C/C++ Language Support. I can build, run, and debug simple C programs fine.</p>
  
  <p>But I'm using some C99 features now, and Eclipse complains, saying "'for' loop initial declarations are only allowed in C99 mode".</p>
  
  <p>I thought you'd set C99 mode for GCC in the makefile, but the makefile is auto-generated by Eclipse so any changes I make would be overwritten, but I don't see anywhere to put GCC compiler options anywhere in Eclipse's preferences nor my Project Properties windows.</p>
  
  <p>So where do I define C99 mode?</p>