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[output.iterators]
24 Iterators library [iterators]
24.3 Iterator requirements [iterator.requirements]
24.3.5 C++17 iterator requirements [iterator.cpp17]
24.3.5.4 Output iterators [output.iterators]
A class or pointer typeX meets the requirements of an output iterator if X meets the Cpp17Iterator requirements ([iterator.iterators]) and the expressions in Table 80 are valid and have the indicated semantics.
Table 80 — Cpp17OutputIterator requirements (in addition to Cpp17Iterator) [tab:outputiterator]
| ð Expression |
Return type | Operational | Assertion/note |
|---|---|---|---|
| ð | semantics | pre-/post-condition | |
| ð *r = o |
result is not used | Remarks: After this operation r is not required to be dereferenceable. Postconditions: r is incrementable. |
|
| ð ++r |
X& | addressof(r) == addressof(++r). Remarks: After this operation r is not required to be dereferenceable. Postconditions: r is incrementable. |
|
| ð r++ |
convertible to const X& | { X tmp = r; ++r; return tmp; } | Remarks: After this operation r is not required to be dereferenceable. Postconditions: r is incrementable. |
| ð *r++ = o |
result is not used | Remarks: After this operation r is not required to be dereferenceable. Postconditions: r is incrementable. |
Recommended practice: The implementation of an algorithm on output iterators should never attempt to pass through the same iterator twice; such an algorithm should be a single-pass algorithm.
[Note 1:
The only valid use of an operator* is on the left side of the assignment statement.
Assignment through the same value of the iterator happens only once.
Equality and inequality are not necessarily defined.
â end note]