std::basic_string_view<CharT,Traits>::copy
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                    |   size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const;  | 
 (since C++17)  (until C++20)  | 
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|   constexpr size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const;  | 
(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).
Parameters
| dest | - | pointer to the destination character string | 
| pos | - | position of the first character | 
| count | - | requested substring length | 
Return value
Number of characters copied
Exceptions
std::out_of_range if pos > size().
Complexity
Linear in rcount.
See also
|    returns a substring  (public member function)  |