6. valgrind - a Memory Problems Detector

• valgrind can detect problems such as:
  
  • Use of uninitialized memory.
  • Reading/writing memory after it has been free()ed.
  • Reading/writing off the end of malloc()ed blocks.
  • Reading/writing inappropriate areas on the stack.
  • Memory leaks -- where pointers to malloc'd blocks are lost forever.
  • Passing of uninitialized and/or unaddressable memory to system calls.
  • Mismatched use of malloc()/new/new [] vs free()/delete/delete [].
  • Some abuses of the POSIX pthreads API.
• valgrind is very easy to use. It has many optional flags that you can learn about from the documentation. (valgrind -h).
• A useful flag is --num-callers=NNN which sets how far back to print the function call sequence when an error is detected, (sometimes the error actually occurs in a sequence of functions you didn't write). By default it is --num-callers=4.

Written by Shlomi Fish