“std::bad_alloc”: am I using too much memory?

Question

The message:

terminate called after throwing an instance of \'std::bad_alloc\'
what():  std::bad_alloc

I looked at the gdb backtrace and

Answer 1

I got this error trying to allocate a negative length array:

double myArray = new double[-9000];

Just in case it helps anyone.

Answer 2

(moving/expanding from the comments)

Since you are allocating a new array every time without deallocating it, you have a massive memory leak, i.e. you continue to ask memory to the system without ever giving it back. Eventually the space on the heap finishes, and at the next allocation all you get is a std::bad_alloc exception.

The "C-style" solution would be to remember to deallocate such memory when you don't need it anymore (with delete[]), but, this is (1) error-prone (think e.g. if you have multiple return paths inside a function) and (2) potentially exception-unsafe (every instruction becomes a potential return path if you have exceptions!). Thus, this way should be avoided.

The idiomatic C++ solution is to use either smart pointers - small objects that encapsulate the pointer and deallocate the associated memory when they are destroyed - or standard containers, that do more or less the same thing but with copy semantics and some more bells and whistles (including storing the size of the array inside them).

Answer 3

My problem turned out to be that this->meshPoints.getNormalForVertex(i) accesses an array (or vector, I can't remember) whose length is less than this->meshPoints.getNumFaces() * 3. So it was accessing out of bounds.