Difference between revisions of "cpp/string/basic string/operator basic string view"
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Revision as of 03:26, 20 October 2023
operator std::basic_string_view<CharT, Traits>() const noexcept; |
(since C++17) (until C++20) |
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| constexpr operator std::basic_string_view<CharT, Traits>() const noexcept; |
(since C++20) | |
Returns a std::basic_string_view, constructed as if by std::basic_string_view<CharT, Traits>(data(), size()).
Contents |
Parameters
(none)
Return value
A string view representing the entire contents of the string.
Notes
It is the programmer's responsibility to ensure that the resulting string view does not outlive the string.
std::string get_string(); int f(std::string_view sv); int x = f(get_string()); // OK std::string_view sv = get_string(); // Bad: holds a dangling pointer
Example
Run this code
#include <iostream> #include <string> #include <string_view> void show_wstring_size(std::wstring_view wcstr_v) { std::cout << wcstr_v.size() << " code points\n"; } int main() { std::string cppstr = "ラーメン"; // narrow string std::wstring wcstr = L"ラーメン"; // wide string // Implicit conversion from string to string_view // via std::string::operator string_view: std::string_view cppstr_v = cppstr; std::cout << cppstr_v << '\n' << cppstr_v.size() << " code units\n"; // Implicit conversion from wstring to wstring_view // via std::wstring::operator wstring_view: show_wstring_size(wcstr); }
Output:
ラーメン 12 code units 4 code points
See also
constructs a basic_string_view (public member function of std::basic_string_view<CharT,Traits>)
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