Difference between revisions of "cpp/iterator/size"
From cppreference.com
(Created page with "{{cpp/title| size}} {{cpp/iterator/navbar}} {{dcl begin}} {{dcl header | iterator}} {{dcl | num=1 | since=c++17 | template < class C> constexpr auto size (const C& c) -> declt...") |
|||
| Line 26: | Line 26: | ||
===Return value=== | ===Return value=== | ||
The size of {{tt|c}} or {{tt|array}} | The size of {{tt|c}} or {{tt|array}} | ||
| + | |||
| + | ===Exceptions=== | ||
| + | @2@ {{noexcept}} | ||
===Notes=== | ===Notes=== | ||
In addition to being included in {{tt|<iterator>}}, {{tt|std::size}} is guaranteed to become available if any of the following headers are included: {{tt|<array>}}, {{tt|<deque>}}, {{tt|<forward_list>}}, {{tt|<list>}}, {{tt|<map>}}, {{tt|<regex>}}, {{tt|<set>}}, {{tt|<string>}}, {{tt|<unordered_map>}}, {{tt|<unordered_set>}}, and {{tt|<vector>}}. | In addition to being included in {{tt|<iterator>}}, {{tt|std::size}} is guaranteed to become available if any of the following headers are included: {{tt|<array>}}, {{tt|<deque>}}, {{tt|<forward_list>}}, {{tt|<list>}}, {{tt|<map>}}, {{tt|<regex>}}, {{tt|<set>}}, {{tt|<string>}}, {{tt|<unordered_map>}}, {{tt|<unordered_set>}}, and {{tt|<vector>}}. | ||
| + | |||
| + | ===Example=== | ||
| + | {{example | ||
| + | | | ||
| + | | code=#include <iostream> | ||
| + | #include <vector> | ||
| + | #include <iterator> | ||
| + | |||
| + | int main() | ||
| + | { | ||
| + | std::vector<int> v = { 3, 1, 4 }; | ||
| + | std::cout << std::size(v) << '\n'; | ||
| + | |||
| + | int a[] = { -5, 10, 15 }; | ||
| + | std::cout << std::size(a) << '\n'; | ||
| + | } | ||
| + | | output= | ||
| + | 3 | ||
| + | 3 | ||
| + | }} | ||
Revision as of 09:20, 15 January 2015
| Defined in header <iterator>
|
||
| template < class C> constexpr auto size (const C& c) -> decltype(c.size()); |
(1) | (since C++17) |
| template <class T, size_t N> constexpr size_t size(const T (&array)[N]) noexcept; |
(2) | (since C++17) |
Returns the size of the given container c or array array.
1) Returns
c.size().2) Returns
N.Contents |
Parameters
| c | - | a container with a size method
|
| array | - | an array of arbitrary type |
Return value
The size of c or array
Exceptions
2)
noexcept specification:
noexcept
Notes
In addition to being included in <iterator>, std::size is guaranteed to become available if any of the following headers are included: <array>, <deque>, <forward_list>, <list>, <map>, <regex>, <set>, <string>, <unordered_map>, <unordered_set>, and <vector>.
Example
Run this code
#include <iostream> #include <vector> #include <iterator> int main() { std::vector<int> v = { 3, 1, 4 }; std::cout << std::size(v) << '\n'; int a[] = { -5, 10, 15 }; std::cout << std::size(a) << '\n'; }
Output:
3 3
