Category: iterators | Component type: concept |
Value type | The type of the value obtained by dereferencing an Input Iterator |
Distance type | A signed integral type used to represent the distance from one iterator to another, or the number of elements in a range. |
X | A type that is a model of Input Iterator |
T | The value type of X |
i, j | Object of type X |
t | Object of type T |
An iterator is valid if it is dereferenceable or past-the-end.
An iterator i is incrementable if there is a "next" iterator, that is, if ++i is well-defined. Past-the-end iterators are not incrementable.
An Input Iterator j is reachable from an Input Iterator i if, after applying operator++ to i a finite number of times, i == j. [1]
The notation [i,j) refers to a range of iterators beginning with i and up to but not including j.
The range [i,j) is a valid range if both i and j are valid iterators, and j is reachable from i [2].
Name | Expression | Type requirements | Return type |
---|---|---|---|
Preincrement | ++i | X& | |
Postincrement | (void)i++ | ||
Postincrement and dereference | *i++ | T |
Name | Expression | Precondition | Semantics | Postcondition |
---|---|---|---|---|
Dereference | *i | i is incrementable | ||
Preincrement | ++i | i is dereferenceable | i is dereferenceable or past-the-end [3] [4] | |
Postincrement | (void)i++ | i is dereferenceable | Equivalent to (void)++i | i is dereferenceable or past-the-end [3] [4] |
Postincrement and dereference | *i++ | i is dereferenceable | Equivalent to {T t = *i; ++i; return t;} | i is dereferenceable or past-the-end [3] [4] |
[1] i == j does not imply ++i == ++j.
[2] Every iterator in a valid range [i, j) is dereferenceable, and j is either dereferenceable or past-the-end. The fact that every iterator in the range is dereferenceable follows from the fact that incrementable iterators must be dereferenceable.
[3] After executing ++i, it is not required that copies of the old value of i be dereferenceable or that they be in the domain of operator==.
[4] It is not guaranteed that it is possible to pass through the same input iterator twice.