Standard Template Library Programmer's Guide

Swap	a.swap(b)	void

Expression semantics

Semantics of an expression is defined only where it differs from, or is not defined in, Assignable, Equality Comparable, or LessThan Comparable

Name	Expression	Semantics	Postcondition
Copy constructor	X(a)		X().size() == a.size(). X() contains a copy of each of a 's elements.
Copy constructor	X b(a);		b.size() == a.size(). b contains a copy of each of a 's elements.
Assignment operator	b = a		b.size() == a.size(). b contains a copy of each of a 's elements.
Destructor	a.~X()	Each of a 's elements is destroyed, and memory allocated for them (if any) is deallocated.
Beginning of range	a.begin()	Returns an iterator pointing to the first element in the container. [7]	a.begin() is either dereferenceable or past-the-end. It is past-the-end if and only if a.size() == 0.
End of range	a.end()	Returns an iterator pointing one past the last element in the container.	a.end() is past-the-end.
Size	a.size()	Returns the size of the container, that is, its number of elements. [8]	a.size() >= 0 && a.size() <= max_size()
Maximum size	a.max_size()	Returns the largest size that this container can ever have. [8]	a.max_size() >= 0 && a.max_size() >= a.size()
Empty container	a.empty()	Equivalent to a.size() == 0. (But possibly faster.)
Swap	a.swap(b)	Equivalent to swap(a,b) [9]

Complexity guarantees

The copy constructor, the assignment operator, and the destructor are linear in the container's size.

begin() and end() are amortized constant time.

size() is linear in the container's size. [10]max_size() and empty() are amortized constant time. If you are testing whether a container is empty, you should always write c.empty() instead of c.size() == 0. The two expressions are equivalent, but the former may be much faster.

swap() is amortized constant time. [9]

Invariants

Valid range

For any container a, [a.begin(), a.end()) is a valid range. [11]