Does std::sort check if a vector is already sorted?

Question

I believe that the C++ standard for std::sort does not guarantee O(n) performance on a list that\'s already sorted. But still, I\'m wondering whether to your knowledge any i

Answer 1

And why would any implementation do that check? What would it gain? -- Nothing in average. A good design rule is not to clutter implementation with optimizations for corner cases which make no difference in average. This example is similar to check for self-assignment. A simple answer: don't do it.