C++ concepts: ForwardIterator

 

C++

Language

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

C++ concepts

Basic
DefaultConstructible CopyAssignable CopyConstructible	MoveAssignable (C++11) MoveConstructible (C++11) Destructible
Library-Wide
EqualityComparable LessThanComparable Swappable (C++11) ValueSwappable (C++11)	NullablePointer (C++11) Hash (C++11) Allocator
Container
Container SequenceContainer ReversibleContainer	AssociativeContainer AllocatorAwareContainer UnorderedAssociativeContainer (C++11)
Container Elements
CopyInsertable (C++11) MoveInsertable (C++11)	EmplaceConstructible (C++11)
Iterator
Iterator OutputIterator InputIterator	ForwardIterator BidirectionalIterator RandomAccessIterator
Stream I/O
FormattedInputFunction UnformattedInputFunction	FormattedOutputFunction UnformattedOutputFunction
Random Numbers
SeedSequence (C++11) RandomNumberEngine (C++11)	RandomNumberDistribution (C++11) UniformRandomNumberGenerator (C++11) RandomNumberEngineAdaptor (C++11)
Concurrency
BasicLockable (C++11) Lockable (C++11) TimedLockable (C++11)	Mutex (C++11) TimedMutex (C++11)
Other
CharTraits pos_type off_type Clock (C++11)	UnaryTypeTrait (C++11) BinaryTypeTrait (C++11) TransformationTrait (C++11) TrivialClock (C++11)

 

A ForwardIterator is an Iterator that can read data from the pointed-to element.

Unlike an InputIterator, it guarantees validity when used in multipass algorithms.

Requirements

• InputIterator
• DefaultConstructible
• a == b implies ++a == ++b

In addition to the above requirements, for a type It to be an Forwardterator, an instance i of It must:

Expression	Return	Equivalent expression	Notes
++i	const It&		After this, copies of i are still valid
i++		value_type temp = *i; ++i; return temp;
*i++	reference

A mutable ForwardIterator is a ForwardIterator that additionally satisfies the OutputIterator requirements.