Free C/C++ Source Code
CIS 71: Some Simple C Programs
These are basic programs for school exercises, from an introductory course in C from the Fall of 2010.
Planet Source Code
1,361,752. lines of C/ C++ code, arranged into categories and with filters for beginner, advanced, etc.
C++ Source Codes
652 C and C++ source code examples. It appears they are distributed under the GNU LGPL license.
Free C/C++ projects with source code.
Bob Stout's SNIPPETS
General-purpose header files, miscellaneous C-callable functions, portable file operations, assorted math functions - I'd need three pages just to describe all the free source code and you can view it or download it as a ZIP or TAR file.
C++ Nugget Mine
A collection of succinct C++ code examples.
Mozilla Source Code
The complete C/C++ source code for the Mozilla open source web browser. You can browse the up-to-the-minute latest version of the source code online and find instructions on building the latest version.