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| − | {{cpp/title|array}}
| + | hello world! |
| − | {{cpp/container/array/navbar}}
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| − | {{ddcl|header=array|since=c++11|
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| − | template<
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| − | class T,
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| − | std::size_t N
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| − | > struct array;
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| − | }}
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| − | {{tt|std::array}} is a container that encapsulates fixed size arrays.
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| − | This container is an aggregate type with the same semantics as a struct holding a [[cpp/language/array|C-style array]] {{c|T[N]}} as its only non-static data member. Unlike a C-style array, it doesn't decay to {{c|T*}} automatically. As an aggregate type, it can be initialized with [[cpp/language/aggregate initialization|aggregate-initialization]] given at most {{tt|N}} initializers that are convertible to {{tt|T}}: {{c|1=std::array<int, 3> a = {1, 2, 3};}}.
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| − | The struct combines the performance and accessibility of a C-style array with the benefits of a standard container, such as knowing its own size, supporting assignment, random access iterators, etc.
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| − | {{tt|std::array}} satisfies the requirements of {{named req|Container}} and {{named req|ReversibleContainer}} except that default-constructed array is not empty and that the complexity of swapping is linear, {{rev inl|since=c++17|satisfies the requirements of {{named req|ContiguousContainer}},}} and partially satisfies the requirements of {{named req|SequenceContainer}}.
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| − | There is a special case for a zero-length array ({{tt|1=N == 0}}). In that case, {{c|
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| − | 1=array.begin() == array.end()}}, which is some unique value. The effect of calling {{c|front()}} or {{c|back()}} on a zero-sized array is undefined.
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| − | An array can also be used as a tuple of {{tt|N}} elements of the same type.
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| − | ===Iterator invalidation===
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| − | As a rule, iterators to an array are never invalidated throughout the lifetime of the array. One should take note, however, that during {{rl|swap}}, the iterator will continue to point to the same array element, and will thus change its value.
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| − | ===Member types===
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| − | {{dsc begin}}
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| − | {{dsc hitem|Member type|Definition}}
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| − | {{dsc inc|cpp/container/dsc value_type|array}}
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| − | {{dsc inc|cpp/container/dsc size_type|array}}
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| − | {{dsc inc|cpp/container/dsc difference_type|array}}
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| − | {{dsc inc|cpp/container/dsc reference|array}}
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| − | {{dsc inc|cpp/container/dsc const_reference|array}}
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| − | {{dsc inc|cpp/container/dsc pointer|array}}
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| − | {{dsc inc|cpp/container/dsc const_pointer|array}}
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| − | {{dsc inc|cpp/container/dsc iterator|array}}
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| − | {{dsc inc|cpp/container/dsc const_iterator|array}}
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| − | {{dsc inc|cpp/container/dsc reverse_iterator|array}}
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| − | {{dsc inc|cpp/container/dsc const_reverse_iterator|array}}
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| − | {{dsc end}}
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| − | ===Member functions===
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| − | {{dsc begin}}
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| − | {{dsc h2|Implicitly-defined member functions}}
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| − | {{dsc mem ctor|nolink=true|notes={{mark implicit}}|initializes the array following the rules of [[cpp/language/aggregate initialization|aggregate initialization]] (note that default initialization may result in indeterminate values for non-class {{tt|T}})}}
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| − | {{dsc mem dtor|nolink=true|notes={{mark implicit}}|destroys every element of the array}}
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| − | {{dsc mem fun|operator{{=}}|nolink=true|notes={{mark implicit}}|overwrites every element of the array with the corresponding element of another array}}
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| − | {{dsc h2|Element access}}
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| − | {{dsc inc|cpp/container/dsc at|array}}
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| − | {{dsc inc|cpp/container/dsc operator_at|array}}
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| − | {{dsc inc|cpp/container/dsc front|array}}
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| − | {{dsc inc|cpp/container/dsc back|array}}
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| − | {{dsc inc|cpp/container/dsc data|array}}
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| − | {{dsc h2|Iterators}}
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| − | {{dsc inc|cpp/container/dsc begin|array}}
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| − | {{dsc inc|cpp/container/dsc end|array}}
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| − | {{dsc inc|cpp/container/dsc rbegin|array}}
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| − | {{dsc inc|cpp/container/dsc rend|array}}
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| − | {{dsc h2|Capacity}}
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| − | {{dsc inc|cpp/container/dsc empty|array}}
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| − | {{dsc inc|cpp/container/dsc size|array}}
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| − | {{dsc inc|cpp/container/dsc max_size|array}}
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| − | {{dsc h2|Operations}}
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| − | {{dsc inc|cpp/container/dsc fill|array}}
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| − | {{dsc inc|cpp/container/dsc swap|array}}
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| − | {{dsc end}}
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| − | ===Non-member functions===
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| − | {{dsc begin}}
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| − | {{dsc inc|cpp/container/dsc operator_cmp|array}}
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| − | {{dsc inc|cpp/container/array/dsc get}}
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| − | {{dsc inc|cpp/container/dsc swap2|array}}
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| − | {{dsc inc|cpp/container/array/dsc to_array}}
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| − | {{dsc end}}
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| − | ===Helper classes===
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| − | {{dsc begin}}
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| − | {{dsc inc|cpp/container/array/dsc tuple_size}}
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| − | {{dsc inc|cpp/container/array/dsc tuple_element}}
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| − | {{dsc end}}
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| − | {{rrev|noborder=true|since=c++17|{{=}}{{=}}{{=}}{{rl|deduction guides|Deduction guides}}{{=}}{{=}}{{=}}}}
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| − | ===Example===
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| − | {{example
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| − | |code=
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| − | #include <algorithm>
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| − | #include <array>
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| − | #include <iostream>
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| − | #include <iterator>
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| − | #include <string>
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| − | int main()
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| − | {
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| − | // Construction uses aggregate initialization
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| − | std::array<int, 3> a1{<!---->{1, 2, 3}<!---->}; // Double-braces required in C++11 prior to
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| − | // the CWG 1270 revision (not needed in C++11
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| − | // after the revision and in C++14 and beyond)
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| − | std::array<int, 3> a2 = {1, 2, 3}; // Double braces never required after =
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| − | // Container operations are supported
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| − | std::sort(a1.begin(), a1.end());
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| − | std::ranges::reverse_copy(a2, std::ostream_iterator<int>(std::cout, " "));
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| − | std::cout << '\n';
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| − | // Ranged for loop is supported
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| − | std::array<std::string, 2> a3{"E", "\u018E"};
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| − | for (const auto& s : a3)
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| − | std::cout << s << ' ';
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| − | std::cout << '\n';
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| − | // Deduction guide for array creation (since C++17)
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| − | [[maybe_unused]] std::array a4{3.0, 1.0, 4.0}; // std::array<double, 3>
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| − | // Behavior of unspecified elements is the same as with built-in arrays
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| − | [[maybe_unused]] std::array<int, 2> a5; // No list init, a5[0] and a5[1]
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| − | // are default initialized
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| − | [[maybe_unused]] std::array<int, 2> a6{}; // List init, both elements are value
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| − | // initialized, a6[0] = a6[1] = 0
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| − | [[maybe_unused]] std::array<int, 2> a7{1}; // List init, unspecified element is value
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| − | // initialized, a7[0] = 1, a7[1] = 0
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| − | }
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| − | |output=
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| − | 3 2 1
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| − | E Ǝ
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| − | }}
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| − | ===See also===
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| − | {{dsc begin}}
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| − | {{dsc inc|cpp/experimental/dsc make array}}
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| − | {{dsc end}}
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| − | {{langlinks|de|es|fr|it|ja|pl|pt|ru|zh}}
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