Difference between revisions of "cpp/string/basic string view/copy"
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size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const; | size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const; | ||
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Copies the substring {{range|pos|pos + rcount}} to the character array pointed to by {{c|dest}}, where {{tt|rcount}} is the smaller of {{c|count}} and {{c|size() - pos}}. | Copies the substring {{range|pos|pos + rcount}} to the character array pointed to by {{c|dest}}, where {{tt|rcount}} is the smaller of {{c|count}} and {{c|size() - pos}}. | ||
Latest revision as of 15:09, 29 April 2024
| size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const; |
(since C++17) (constexpr since C++20) |
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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).
Contents |
[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'); source.copy(dest.data(), count = 4); // pos = 0 std::cout << dest.data() << '\n'; // ABCD dest.fill('\0'); source.copy(dest.data(), count = 4, pos = 1); std::cout << dest.data() << '\n'; // BCDE dest.fill('\0'); 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)
[edit] See also
| returns a substring (public member function) | |
| copies characters (public member function of std::basic_string<CharT,Traits,Allocator>)
| |
| (C++11) |
copies a range of elements to a new location (function template) |
| copies one buffer to another (function) |
