Difference between revisions of "Template:cpp/container/data"
From cppreference.com
m (+ link to std::data) |
(https://cplusplus.github.io/LWG/issue464 wasn't opened until 2004, so std::vector::data wasn't included until c++11) |
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T* data();<!-- LWG 464 --> | T* data();<!-- LWG 464 --> | ||
| − | | since{{#switch:{{{1|}}}|array=1|vector= | + | | since{{#switch:{{{1|}}}|array=1|vector=1}}=c++11 | dcl{{#switch:{{{1|}}}|array=1|vector=1}}= |
T* data() noexcept; | T* data() noexcept; | ||
| − | | since{{#switch:{{{1|}}}|array=2|vector= | + | | since{{#switch:{{{1|}}}|array=2|vector=2}}={{#switch:{{{1|}}}|array=c++17|vector=c++20}} | dcl{{#switch:{{{1|}}}|array=2|vector=2}}= |
constexpr T* data() noexcept; | constexpr T* data() noexcept; | ||
}} | }} | ||
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const T* data() const;<!-- LWG 464 --> | const T* data() const;<!-- LWG 464 --> | ||
| − | | since{{#switch:{{{1|}}}|array=1|vector= | + | | since{{#switch:{{{1|}}}|array=1|vector=1}}=c++11 | dcl{{#switch:{{{1|}}}|array=1|vector=1}}= |
const T* data() const noexcept; | const T* data() const noexcept; | ||
| − | | since{{#switch:{{{1|}}}|array=2|vector= | + | | since{{#switch:{{{1|}}}|array=2|vector=2}}={{#switch:{{{1|}}}|array=c++17|vector=c++20}} | dcl{{#switch:{{{1|}}}|array=2|vector=2}}=constexpr const T* data() const noexcept; |
}} | }} | ||
{{dcl end}} | {{dcl end}} | ||
Revision as of 18:04, 8 July 2022
T* data(); |
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const T* data() const; |
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Returns pointer to the underlying array serving as element storage. The pointer is such that range [data(); data() + size()) is always a valid range, even if the container is empty (data() is not dereferenceable in that case).
Contents |
Parameters
(none)
Return value
Pointer to the underlying element storage. For non-empty containers, the returned pointer compares equal to the address of the first element.
Complexity
Constant.
Notes
If size() is 0, data() may or may not return a null pointer.
Example
Run this code
#include <cstddef> #include <iostream> #include <span> #include <{{{1}}}> void pointer_func(const int* p, std::size_t size) { std::cout << "data = "; for (std::size_t i = 0; i < size; ++i) std::cout << p[i] << ' '; std::cout << '\n'; } void span_func(std::span<const int> data) // since C++20 { std::cout << "data = "; for (const int e : data) std::cout << e << ' '; std::cout << '\n'; } int main() { std::{{{1}}}<int> container { 1, 2, 3, 4 }; // Prefer container.data() over &container[0] pointer_func(container.data(), container.size()); // std::span (C++20) is a safer alternative to separated pointer/size. span_func({container.data(), container.size()}); }
Output:
data = 1 2 3 4 data = 1 2 3 4
See also
| access the first element (public member function of std::{{{1}}})
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| access the last element (public member function of std::{{{1}}})
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| returns the number of elements (public member function of std::{{{1}}})
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| (C++20) |
a non-owning view over a contiguous sequence of objects (class template) |
| (C++17) |
obtains the pointer to the underlying array (function template) |
