std::basic_string_view<CharT,Traits>::basic_string_view
constexpr basic_string_view() noexcept; | (1) | (since C++17) |
constexpr basic_string_view(const basic_string_view& other) noexcept = default; | (2) | (since C++17) |
constexpr basic_string_view(const CharT* s, size_type count); | (3) | (since C++17) |
constexpr basic_string_view(const CharT* s); | (4) | (since C++17) |
1) Default constructor. Constructs an empty
basic_string_view
. After construction, data()
is equal to nullptr
, and size()
is equal to 0
.
2) Copy constructor. Constructs a view of the same content as
other
. After construction, data()
is equal to other.data()
, and size()
is equal to other.size()
.
3) Constructs a view of the first
count
characters of the character array starting with the element pointed by s
. s
can contain null characters. The behavior is undefined if [s, s+count)
is not a valid range (even though the constructor may not access any of the elements of this range). After construction, data()
is equal to s
, and size()
is equal to count
.
4) Constructs a view of the null-terminated character string pointed to by
s
, not including the terminating null character. The length of the view is determined as if by Traits::length(s)
. The behavior is undefined if [s, s+Traits::length(s))
is not a valid range. After construction, data()
is equal to s
, and size()
is equal to Traits::length(s)
.Parameters
other | - | another view to initialize the view with |
s | - | pointer to a character array or a C string to initialize the view with |
count | - | number of characters to include in the view |
Complexity
1-3) constant
4) linear in length of
s
Example
#include <iostream> #include <string> #include <string_view> int main() { std::wstring_view wcstr_v = L"xyzzy"; char array[3] = {'B', 'a', 'r'}; std::string_view array_v(array, std::size(array)); std::string cppstr = "Foo"; std::string_view cppstr_v(cppstr); std::cout << cppstr_v << '\n' << array_v << '\n' << wcstr_v.size() << '\n'; }
Output:
Foo Bar 5
See also
assigns a view (public member function) |
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