Concept InputIterator

Concept InputIterator 輸入迭代器概念

InputIterator 輸入迭代器

Description 說明

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.
輸入迭代器是一種可以讀入一組值的序列的迭代器。它是單遍的(迭代器的舊值不可重用)和只讀的。

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).
輸入迭代器表示了在一個序列中的某個位置。因此，迭代器可以指向序列內部(在提領時返回一個值且可以遞增)，或者指向序列末端之後(不可提領且不可遞增)。

Refinement of 精化自

Associated types 關聯類型

value_type
```
std::iterator_traits<Iter>::value_type
```
The value type of the iterator (not necessarily what *i returns)
迭代器的值類型(不一定是 *i 所返回的)
difference_type
```
std::iterator_traits<Iter>::difference_type
```
The difference type of the iterator
迭代器的距離類型
category
```
std::iterator_traits<Iter>::iterator_category
```
The category of the iterator
迭代器的類別

Notation 符號

Iter: A type playing the role of iterator-type in the InputIterator concept.; 在輸入迭代器概念中擔任迭代器類型角色的類型。
i, j: Objects of type Iter; 類型 Iter 的對象
x: Object of type value_type; 類型 value_type 的對象

Type expressions 類型表達式

Category tag 類別標記: category must be derived from std::input_iterator_tag, a model of DefaultConstructible, and a model of CopyConstructible.; category 必須派生自 std::input_iterator_tag，且可缺省構造和可複製構造。
Value type copy constructibility 值類型的可複製構造性: value_type must be a model of CopyConstructible.; value_type 必須為可複製構造。
Difference type properties 距離類型的屬性: difference_type must be a model of SignedInteger.; difference_type 必須為有符號整數。

Valid expressions 有效表達式

Name 名字	Expression 表達式	Type 類型	Precondition 前置條件	Semantics 語義	Postcondition 後置條件
Dereference 提領	*i	Convertible to value_type 可轉換為 value_type	`i` is incrementable (not off-the-end) `i` 是可遞增的(不是 off-the-end)
Preincrement 前綴遞增	++i	Iter &	`i` is incrementable (not off-the-end) `i` 是可遞增的(不是 off-the-end)
Postincrement 後綴遞增	i++		`i` is incrementable (not off-the-end) `i` 是可遞增的(不是 off-the-end)	Equivalent to `(void)(++i)` 等價於 `(void)(++i)`	`i` is dereferenceable or off-the-end `i` 為可提領的或 off-the-end
Postincrement and dereference 後綴遞增並提領	*i++	Convertible to value_type 可轉換為 value_type	`i` is incrementable (not off-the-end) `i` 是可遞增的(不是 off-the-end)	Equivalent to `{value_type t = i; ++i; return t;}` `等價於` `{value_type t = i; ++i; return t;}`	`i` is dereferenceable or off-the-end `i` 為可提領的或 off-the-end

Complexity 複雜度

All iterator operations must take amortized constant time.
迭代器的所有操作必須為分期常量時間複雜度。

Models 模型

std::istream_iterator