std::basic_string_view

 

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Technical Specifications

 

Strings library

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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<< operator""sv Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u16string_view>hash<std::u32string_view>

 

Defined in header <string_view>
template<     class CharT,     class Traits = std::char_traits<CharT> > class basic_string_view;		(since C++17)

The class template basic_string_view describes an object that can refer to a constant contiguous sequence of char-like objects with the first element of the sequence at position zero.

A typical implementation holds only two members: a pointer to constant CharT and a size.

Several typedefs for common character types are provided:

Defined in header <string_view>
Type	Definition
std::string_view	std::basic_string_view<char>
std::wstring_view	std::basic_string_view<wchar_t>
std::u8string_view	std::basic_string_view<char8_t> (C++20)
std::u16string_view	std::basic_string_view<char16_t>
std::u32string_view	std::basic_string_view<char32_t>

Template parameters

CharT	-	character type
Traits	-	CharTraits class specifying the operations on the character type. Like for basic_string, Traits::char_type must name the same type as CharT or the program is ill-formed.

Member types

Member type	Definition
traits_type	Traits
value_type	CharT
pointer	CharT*
const_pointer	const CharT*
reference	CharT&
const_reference	const CharT&
const_iterator	implementation-defined constant LegacyRandomAccessIterator, ConstexprIterator (since C++20) and LegacyContiguousIterator whose value_type is CharT
iterator	const_iterator
reverse_iterator	const_reverse_iterator
const_reverse_iterator	std::reverse_iterator<const_iterator>
size_type	std::size_t
difference_type	std::ptrdiff_t

Note: iterator and const_iterator are the same type because string views are views into constant character sequences.

All requirements on the iterator types of a Container applies to the iterator and const_iterator types of basic_string_view as well.

Member functions

(constructor)	constructs a basic_string_view (public member function)
operator=	assigns a view (public member function)
Iterators
begincbegin	returns an iterator to the beginning (public member function)
endcend	returns an iterator to the end (public member function)
rbegincrbegin	returns a reverse iterator to the beginning (public member function)
rendcrend	returns a reverse iterator to the end (public member function)
Element access
operator[]	accesses the specified character (public member function)
at	accesses the specified character with bounds checking (public member function)
front	accesses the first character (public member function)
back	accesses the last character (public member function)
data	returns a pointer to the first character of a view (public member function)
Capacity
sizelength	returns the number of characters (public member function)
max_size	returns the maximum number of characters (public member function)
empty	checks whether the view is empty (public member function)
Modifiers
remove_prefix	shrinks the view by moving its start forward (public member function)
remove_suffix	shrinks the view by moving its end backward (public member function)
swap	swaps the contents (public member function)
Operations
copy	copies characters (public member function)
substr	returns a substring (public member function)
compare	compares two views (public member function)
starts_with (C++20)	checks if the string view starts with the given prefix (public member function)
ends_with (C++20)	checks if the string view ends with the given suffix (public member function)
find	find characters in the view (public member function)
rfind	find the last occurrence of a substring (public member function)
find_first_of	find first occurrence of characters (public member function)
find_last_of	find last occurrence of characters (public member function)
find_first_not_of	find first absence of characters (public member function)
find_last_not_of	find last absence of characters (public member function)
Constants
npos [static]	special value. The exact meaning depends on the context (public static member constant)

Non-member functions

operator==operator!=operator<operator>operator<=operator>=	lexicographically compares two string views (function template)
beginend (C++20)	returns iterators to the beginning and the end of the string view (function)
Input/output
operator<<	performs stream output on string views (function template)

Literals

Defined in inline namespace std::literals::string_view_literals
operator""sv (C++17)	Creates a string view of a character array literal (function)

Helper classes

std::hash<std::string_view>std::hash<std::wstring_view>std::hash<std::u8string_view>std::hash<std::u16string_view>std::hash<std::u32string_view> (C++17)(C++17)(C++20)(C++17)(C++17)

hash support for string views (class template specialization)

Notes

It is the programmer's responsibility to ensure that std::string_view does not outlive the pointed-to character array:

std::string_view good("a string literal");   // OK: "good" points to a static array
std::string_view bad("a temporary string"s); // "bad" holds a dangling pointer