std::basic_string_view::basic_string_view

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

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 Modifers 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::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<< Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u16string_view>hash<std::u32string_view>

 

constexpr basic_string_view();	(1)	(since C++17)
constexpr basic_string_view(const basic_string_view& other) = 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.

2) Copy constructor. Constructs a view of the same content as other.

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)

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 (even though the constructor may not access any of the elements of this range)

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

Exceptions

1-3)

noexcept specification:  

noexcept

  

Complexity

(1-3) constant

(4) linear in length of s

Notes

Because std::char_traits::length is not constexpr (pending LWG 2232), the overload (4) cannot be used to initialize a constexpr std::string_view (or any other basic_string_view with default traits):

constexpr std::string_view sv{"abc"}; // error
constexpr std::string_view sv{"abc", 3}; // OK

Example

Run this code

#include <iostream>
#include <string_view>
int main()
{
    std::wstring_view wcstr_v = L"xyzzy";
 
    char array[3] = {'B', 'a', 'r'};
    std::string_view array_v(array, sizeof array);
 
    std::string cppstr = "Foo";
    std::string_view cppstr_v(&cppstr[0], cppstr.size()); 
 
    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)