C++ concepts: ForwardIterator

 

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C++ concepts

Basic
DefaultConstructible CopyAssignable CopyConstructible	MoveAssignable (C++11) MoveConstructible (C++11) Destructible
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Iterator OutputIterator InputIterator	ForwardIterator BidirectionalIterator RandomAccessIterator
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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 ForwardIterator, an instance i of It must:

Expression	Return	Equivalent expression	Notes
++i	iterator	i=std::next(i); return i;	After this, copies of i are still valid
i++	iterator	iterator ip=i; i=std::next(i); return ip;
*i++	reference	value_type& temp=*i; ++i; return temp;

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

A value-initialized ForwardIterator behaves like the past-the-end iterator of some unspecified empty container: it compares equal to all value-initialized ForwardIterators of the same type. (since C++14)

See also

• Iterator library