CodeLite is an open source, free, cross platform IDE for the C/C++
and PHP programming languages which runs best on all major platforms
(OS X, Windows and Linux). CodeLite has Generic support for compilers
with built-in support for GCC/clang/VC++.
CodeLite features project management (workspace/projects), code
completion, code refactoring, source browsing, syntax highlight,
Subversion integration, cscope integration, UnitTest++ integration,
an interactive debugger built over GDB/LLDB and a source code editor
(based on Scintilla).

Optional: valgrind