std::basic_string_view<CharT,Traits>::basic_string_view

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string_view

Member functions basic_string_view::basic_string_view basic_string_view::operator= Iterators basic_string_view::beginbasic_string_view::cbegin basic_string_view::endbasic_string_view::cend basic_string_view::rbeginbasic_string_view::crbegin basic_string_view::rendbasic_string_view::crend Element access basic_string_view::at basic_string_view::operator[] basic_string_view::front basic_string_view::back basic_string_view::data Capacity basic_string_view::sizebasic_string_view::length basic_string_view::max_size basic_string_view::empty Modifiers basic_string_view::remove_prefix basic_string_view::remove_suffix basic_string_view::swap

Operations basic_string_view::copy basic_string_view::substr basic_string_view::compare basic_string_view::starts_with (C++20) basic_string_view::ends_with (C++20) basic_string_view::find basic_string_view::rfind basic_string_view::find_first_of basic_string_view::find_last_of basic_string_view::find_first_not_of basic_string_view::find_last_not_of Constants basic_string_view::npos Non-member functions operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) operator<< operator""sv Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u8string_view>hash<std::u16string_view>hash<std::u32string_view> (C++20) Deduction guides(C++20)

 

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)
template<class It, class End> constexpr basic_string_view(It first, End last);	(5)	(since C++20)

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).

5) Constructs a basic_string_view over the range [first, last). The behavior is undefined if [first, last) is not a valid range, if It does not actually model contiguous_iterator, or if End does not actually model sized_sentinel_for for It. After construction, data() is equal to std::to_address(first), and size() is equal to last - first.

This overload only participates in overload resolution if

• It satisfies contiguous_iterator,
• End satisfies sized_sentinel_for for It,
• std::iter_value_t<It> and CharT are the same type, and
• End is not convertible to std::size_t.

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
first	-	iterator to the first character of the sequence
last	-	iterator past the last character of the sequence or another sentinel

Complexity

1-3,5) constant

4) linear in length of s

Example

Run this code

#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

operator=

assigns a view (public member function)