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 qsort implementation which can fail on large arrays is extremely broken. If you're really worried I'd go RTFS, but I suspect any half-decent implementation will either use an in-place sorting algorithm or use malloc for temporary space and fall back to an in-place algorithm if malloc fails.

Answer 2

I remember reading in this book: C Programming: A Modern Approach that the ANSI C specification doesn't define how to implement qsort.

And the book wrote that qsort could in reality be a another kind of sort, merge sort, insertion sort and why not bubble sort :P

So, the qsort implementation might not be recursive.

Answer 3

You know, the recursive part is logn deep. In 64 levels of recursion (which is ~64*4=~256 bytes of stack total) you can sort an array of size ~2^64, ie an array as large as you can address on a 64 bit cpu, which is 147573952589676412928 bytes for 64 bit integers. You can't even hold it in memory!

Worry about stuff that matters imo.