When a program is run under Valgrind's supervision, all reads and
writes of memory are checked, and calls to malloc/new/free/delete are
intercepted. As a result, Valgrind can detect problems such as:

* Use of uninitialised memory
* Reading/writing memory after it has been free'd
* Reading/writing off the end of malloc'd blocks
* Reading/writing inappropriate areas on the stack
* Memory leaks -- where pointers to malloc'd blocks are lost forever
* Passing of uninitialised and/or unaddressible memory to system calls
* Mismatched use of malloc/new/new [] vs free/delete/delete []