std::basic_string_view<CharT,Traits>::copy
From cppreference.com
< cpp | string | basic string view
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
std::basic_string_view
basic_string_view::copy
(C++20)
(C++20)
(C++23)
Constants
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Deduction guides (C++20)
size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const;
(since C++17) (constexpr since C++20)
Copies the substring [pos, pos + rcount) to the character array pointed to by dest, where rcount is the smaller of count and size() - pos.
Equivalent to Traits::copy(dest, data() + pos, rcount).
[edit] Parameters
dest
-
pointer to the destination character string
count
-
requested substring length
pos
-
position of the first character
[edit] Return value
Number of characters copied.
[edit] Exceptions
std::out_of_range if pos > size().
[edit] Complexity
Linear in rcount.
[edit] Example
Run this code
#include <array> #include <cstddef> #include <iostream> #include <stdexcept> #include <string_view> int main() { constexpr std::basic_string_view <char> source{"ABCDEF"}; std::array <char, 8> dest; std::size_t count{}, pos{}; dest.fill('0円'); source.copy(dest.data(), count = 4); // pos = 0 std::cout << dest.data() << '\n'; // ABCD dest.fill('0円'); source.copy(dest.data(), count = 4, pos = 1); std::cout << dest.data() << '\n'; // BCDE dest.fill('0円'); source.copy(dest.data(), count = 42, pos = 2); // ok, count -> 4 std::cout << dest.data() << '\n'; // CDEF try { source.copy(dest.data(), count = 1, pos = 666); // throws: pos > size() } catch (std::out_of_range const& ex) { std::cout << ex.what() << '\n'; } }
Output:
ABCD BCDE CDEF basic_string_view::copy: __pos (which is 666) > __size (which is 6)