operator-(std::common_iterator)

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Compiler support
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Standard library
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Feature test macros(C++20)
Language support library
Concepts library(C++20)
Diagnostics library
Memory management library
Metaprogramming library(C++11)
General utilities library
Containers library
Iterators library
Ranges library(C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library(C++17)
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Iterator library

Iterator concepts

indirectly_readable (C++20)
indirectly_writable (C++20)
weakly_incrementable (C++20)
incrementable (C++20)
is-integer-like is-signed-integer-like (C++20)(C++20)

sentinel_for (C++20)
sized_sentinel_for (C++20)
input_iterator (C++20)
output_iterator (C++20)
input_or_output_iterator (C++20)

forward_iterator (C++20)
bidirectional_iterator (C++20)
random_access_iterator (C++20)
contiguous_iterator (C++20)

Iterator primitives

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag

(C++20)

iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t

(C++20)(C++20)(C++20)(C++23)(C++20)(C++20)

iterator (deprecated in C++17)
iterator_traits
incrementable_traits (C++20)
indirectly_readable_traits (C++20)

Algorithm concepts and utilities

Indirect callable concepts

indirectly_unary_invocableindirectly_regular_unary_invocable

(C++20)(C++20)

indirect_unary_predicate (C++20)
indirect_binary_predicate (C++20)

indirect_equivalence_relation (C++20)
indirect_strict_weak_order (C++20)

Common algorithm requirements

indirectly_movable (C++20)
indirectly_movable_storable (C++20)
indirectly_copyable (C++20)

indirectly_copyable_storable (C++20)
indirectly_swappable (C++20)
indirectly_comparable (C++20)

permutable (C++20)
mergeable (C++20)
sortable (C++20)

(C++20)

(C++20)

(C++26)

reverse_iterator
make_reverse_iterator (C++14)
move_iterator (C++11)
make_move_iterator (C++11)
default_sentinel_tdefault_sentinel (C++20)(C++20)
unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)

front_insert_iterator
back_insert_iterator
inserter
insert_iterator
front_inserter
back_inserter
move_sentinel (C++20)

common_iterator (C++20)
counted_iterator (C++20)
basic_const_iterator (C++23)
const_iterator (C++23)
const_sentinel (C++23)
make_const_iterator (C++23)
make_const_sentinel (C++23)

Stream iterators

istream_iterator
ostream_iterator

istreambuf_iterator
ostreambuf_iterator

Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)

Iterator operations

advance
distance
prev (C++11)
next (C++11)

ranges::advance (C++20)
ranges::distance (C++20)
ranges::prev (C++20)
ranges::next (C++20)

Range access

begincbegin (C++11)(C++14)
rbegincrbegin (C++14)(C++14)

endcend (C++11)(C++14)
rendcrend (C++14)(C++14)

sizessize (C++17)(C++20)
empty (C++17)
data (C++17)

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std::common_iterator

Member functions
common_iterator::common_iterator
common_iterator::operator=
common_iterator::operator*common_iterator::operator->
common_iterator::operator++common_iterator::operator++(int)
Non-member functions
operator== (C++20)
operator- (C++20)
iter_move (C++20)
iter_swap (C++20)
Helper classes
incrementable_traits<std::common_iterator> (C++20)
iterator_traits<std::common_iterator> (C++20)

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template<std::sized_sentinel_for<I> I2,std::sized_sentinel_for<I> S2> requiresstd::sized_sentinel_for<S, I2> friendconstexprstd::iter_difference_t<I2> operator-(const common_iterator& x,conststd::common_iterator<I2, S2>& y);		(since C++20)

Computes the distance between two iterator adaptors. Two sentinels are considered equal.

Letvar denote the underlyingstd::variant member object instd::common_iterator, the behavior is undefined if eitherx ory is invalid, i.e.x.var.valueless_by_exception()|| y.var.valueless_by_exception() istrue.

This function template is not visible to ordinaryunqualified orqualified lookup, and can only be found byargument-dependent lookup when std::common_iterator<I> is an associated class of the arguments.

[edit]Parameters

x, y

iterator adaptors to compute the difference of

[edit]Return value

0 ifx.var holds anS object andy.var holds anS2 object, i.e. both of them hold a sentinel.
Otherwise,alt_x- alt_y, wherealt_x andalt_y are the alternatives held byx.var andy.var, respectively (either two iterators or one iterator and one sentinel).

[edit]Example

Run this code

#include <algorithm>#include <iostream>#include <iterator> int main(){int a[]{0,1,2,3,4,5}; using CI=std::common_iterator<std::counted_iterator<int*>,std::default_sentinel_t>;     CI i1{std::counted_iterator{a+1,2}};    CI i2{std::counted_iterator{a,3}};    CI s1{std::default_sentinel};    CI s2{std::default_sentinel}; std::cout<<(s2- s1)<<' '<<(i2- i1)<<' '<<(i1- s1)<<'\n';}