cppreference std::data

Possible implementation

First version

template<class C>
constexpr auto data(C &c) -> decltype(c.data())
{
    return c.data();
}

NOTE:

测试程序:

#include <vector>
#include <cassert>
template<class C>
constexpr auto data(C &c) -> decltype(c.data())
{
  return c.data();
}

int main()
{
  std::vector<int> v { 1, 2, 3 };
  int *begin = data(v);
  assert(begin == v.data());
}
// g++ test.cpp --std=c++11 -pedantic -Wall -Wextra

Second version

template <class C> 
constexpr auto data(const C& c) -> decltype(c.data())
{
    return c.data();
}

Third version

NOTE:

测试程序:

#include <vector>
#include <cassert>
template<class T, std::size_t N>
constexpr T* data(T (&array)[N]) noexcept
{
  return array;
}

int main()
{
  int v[] { 1, 2, 3 };
  int *begin = data(v);
  assert(begin == v);
}
// g++ test.cpp --std=c++11 -pedantic -Wall -Wextra

Fourth version

template <class E> 
constexpr const E* data(std::initializer_list<E> il) noexcept
{
    return il.begin();
}