Is stdlib's qsort recursive?

Question

I\'ve read that qsort is just a generic sort, with no promises about implementation. I don\'t know about how libraries vary from platform to plaform, but assumi

Answer 1

A properly implemented qsort does not require more than log2(N) levels of recursion (i.e. depth of stack), where N is the largest array size on the given platform. Note that this limit applies regardless of how good or bad the partitioning happens to be, i.e. it is the worst case depth of recursion. For example, on a 32-bit platform, the depth of recursion will never exceed 32 in the worst possible case, given a sane implementation of qsort.

In other words, if you are concerned about the stack usage specifically, you have nothing to worry about, unless you are dealing with some strange low-quality implementation.