size_type capacity() const; | (until C++11) | |
size_type capacity() const noexcept; | (since C++11) (until C++20) | |
constexpr size_type capacity() const noexcept; | (since C++20) |
Returns the number of elements that the container has currently allocated space for.
(none).
Capacity of the currently allocated storage.
Constant.
#include <iomanip> #include <iostream> #include <vector> int main() { int sz = 100; std::vector<int> v; auto cap = v.capacity(); std::cout << "Initial size: " << v.size() << ", capacity: " << cap << '\n'; std::cout << "\nDemonstrate the capacity's growth policy." "\nSize: Capacity: Ratio:\n" << std::left; while (sz-- > 0) { v.push_back(sz); if (cap != v.capacity()) { std::cout << std::setw( 7) << v.size() << std::setw(11) << v.capacity() << std::setw(10) << v.capacity() / static_cast<float>(cap) << '\n'; cap = v.capacity(); } } std::cout << "\nFinal size: " << v.size() << ", capacity: " << v.capacity() << '\n'; }
Possible output:
returns the number of elements (public member function) |
|
reserves storage (public member function) |
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