Difference between revisions of "cpp/iterator/data"
From cppreference.com
m (s/method/member function) |
(+ ranges) |
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{{dcl end}} | {{dcl end}} | ||
| − | Returns a pointer to the block of memory containing the elements of the | + | Returns a pointer to the block of memory containing the elements of the range. |
@1,2@ returns {{c|c.data()}} | @1,2@ returns {{c|c.data()}} | ||
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===Parameters=== | ===Parameters=== | ||
{{par begin}} | {{par begin}} | ||
| − | {{par | c | a container with a {{c|data()}} member function}} | + | {{par | c | a container or view with a {{c|data()}} member function}} |
{{par | array | an array of arbitrary type}} | {{par | array | an array of arbitrary type}} | ||
{{par | il | an initializer list}} | {{par | il | an initializer list}} | ||
| Line 48: | Line 48: | ||
===Return value=== | ===Return value=== | ||
| − | A pointer to the block of memory containing the elements of the | + | A pointer to the block of memory containing the elements of the range. |
| + | |||
| + | ===Exceptions=== | ||
| + | @1@ {{cpp/impldef exception item}} | ||
| + | |||
| + | ===Notes=== | ||
| + | The overload for {{lc|std::initializer_list}} is necessary because it does not have a member function {{tt|data}}. | ||
===Possible implementation=== | ===Possible implementation=== | ||
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}} | }} | ||
| − | {{langlinks|es|ja|zh}} | + | ===See also=== |
| + | {{dsc begin}} | ||
| + | {{dsc inc | cpp/ranges/dsc data}} | ||
| + | {{dsc end}} | ||
| + | |||
| + | {{langlinks|es|ja|ru|zh}} | ||
Revision as of 23:50, 3 April 2021
| Defined in header <array>
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| Defined in header <deque>
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| Defined in header <forward_list>
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| Defined in header <iterator>
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| Defined in header <list>
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| Defined in header <map>
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| Defined in header <regex>
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| Defined in header <set>
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| Defined in header <span>
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(since C++20) |
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| Defined in header <string>
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| Defined in header <string_view>
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| Defined in header <unordered_map>
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| Defined in header <unordered_set>
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| Defined in header <vector>
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| template <class C> constexpr auto data(C& c) -> decltype(c.data()); |
(1) | (since C++17) |
| template <class C> constexpr auto data(const C& c) -> decltype(c.data()); |
(2) | (since C++17) |
| template <class T, std::size_t N> constexpr T* data(T (&array)[N]) noexcept; |
(3) | (since C++17) |
| template <class E> constexpr const E* data(std::initializer_list<E> il) noexcept; |
(4) | (since C++17) |
Returns a pointer to the block of memory containing the elements of the range.
1,2) returns c.data()
3) returns array
4) returns il.begin()
Contents |
Parameters
| c | - | a container or view with a data() member function |
| array | - | an array of arbitrary type |
| il | - | an initializer list |
Return value
A pointer to the block of memory containing the elements of the range.
Exceptions
1) May throw implementation-defined exceptions.
Notes
The overload for std::initializer_list is necessary because it does not have a member function data.
Possible implementation
| First version |
|---|
template <class C> constexpr auto data(C& c) -> decltype(c.data()) { return c.data(); } |
| Second version |
template <class C> constexpr auto data(const C& c) -> decltype(c.data()) { return c.data(); } |
| Third version |
template <class T, std::size_t N> constexpr T* data(T (&array)[N]) noexcept { return array; } |
| Fourth version |
template <class E> constexpr const E* data(std::initializer_list<E> il) noexcept { return il.begin(); } |
Example
Run this code
#include <string> #include <cstring> #include <iostream> int main() { std::string s {"Hello world!\n"}; char a[20]; //storage for a C-style string std::strcpy(a, std::data(s)); //[s.data(), s.data() + s.size()] is guaranteed to be an NTBS since C++11 std::cout << a; }
Output:
Hello world!
See also
| (C++20) |
obtains a pointer to the beginning of a contiguous range (customization point object) |
