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InputIterator
An input iterator is an iterator that can read through a sequence of values. It is single-pass (old values of the iterator cannot be re-used), and read-only.
An input iterator represents a position in a sequence. Therefore, the iterator can point into the sequence (returning a value when dereferenced and being incrementable), or be off-the-end (and not dereferenceable or incrementable).
value_type
std::iterator_traits<Iter>::value_type
The value type of the iterator (not necessarily what *i returns)
difference_type
std::iterator_traits<Iter>::difference_type
The difference type of the iterator
category
std::iterator_traits<Iter>::iterator_category
The category of the iterator
category must be derived from std::input_iterator_tag, a model of DefaultConstructible, and a model of CopyConstructible.
value_type must be a model of CopyConstructible.
difference_type must be a model of SignedInteger.
Name | Expression | Type | Precondition | Semantics | Postcondition |
---|---|---|---|---|---|
Dereference | *i | Convertible to value_type | i is incrementable (not off-the-end) | ||
Preincrement | ++i | Iter & | i is incrementable (not off-the-end) | ||
Postincrement | i++ | i is incrementable (not off-the-end) | Equivalent to (void)(++i) | i is dereferenceable or off-the-end | |
Postincrement and dereference | *i++ | Convertible to value_type | i is incrementable (not off-the-end) | Equivalent to {value_type t = *i; ++i; return t;} | i is dereferenceable or off-the-end |
All iterator operations must take amortized constant time.
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