Standard library header <string_view> (C++17)

 

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Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header is part of the strings library.

Includes
<compare> (C++20)	Three-way comparison operator support
Classes
basic_string_view (C++17)	read-only string view (class template)
std::string_view (C++17)	std::basic_string_view<char>
std::u8string_view (C++20)	std::basic_string_view<char8_t>
std::u16string_view (C++17)	std::basic_string_view<char16_t>
std::u32string_view (C++17)	std::basic_string_view<char32_t>
std::wstring_view (C++17)	std::basic_string_view<wchar_t>
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)
Forward declarations
Defined in header <functional>
hash (C++11)	hash function object (class template)
Functions
operator==operator!=operator<operator>operator<=operator>=operator<=> (C++17)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20)	lexicographically compares two string views (function template)
operator<< (C++17)	performs stream output on string views (function template)
swap	swaps the values of two objects (function template)
Range access
begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)
endcend (C++11)(C++14)	returns an iterator to the end of a container or array (function template)
rbegincrbegin (C++14)	returns a reverse iterator to the beginning of a container or array (function template)
rendcrend (C++14)	returns a reverse end iterator for a container or array (function template)
sizessize (C++17)(C++20)	returns the size of a container or array (function template)
empty (C++17)	checks whether the container is empty (function template)
data (C++17)	obtains the pointer to the underlying array (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)

Synopsis

#include <compare>
 
namespace std {
  // class template basic_string_view
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_string_view;
 
  template<class CharT, class Traits>
    inline constexpr bool ranges::enable_view<basic_string_view<CharT, Traits>> = true;
  template<class CharT, class Traits>
    inline constexpr bool ranges::enable_borrowed_range<basic_string_view<CharT, Traits>> =
      true;
 
  // non-member comparison functions
  template<class CharT, class Traits>
    constexpr bool operator==(basic_string_view<CharT, Traits> x,
                              basic_string_view<CharT, Traits> y) noexcept;
  template<class CharT, class Traits>
    constexpr /* see description */
      operator<=>(basic_string_view<CharT, Traits> x,
                  basic_string_view<CharT, Traits> y) noexcept;
 
  // sufficient additional overloads of comparison functions
 
  // inserters and extractors
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>&
      operator<<(basic_ostream<CharT, Traits>& os,
                 basic_string_view<CharT, Traits> str);
 
  // basic_string_view typedef names
  using string_view    = basic_string_view<char>;
  using u8string_view  = basic_string_view<char8_t>;
  using u16string_view = basic_string_view<char16_t>;
  using u32string_view = basic_string_view<char32_t>;
  using wstring_view   = basic_string_view<wchar_t>;
 
  // hash support
  template<class T> struct hash;
  template<> struct hash<string_view>;
  template<> struct hash<u8string_view>;
  template<> struct hash<u16string_view>;
  template<> struct hash<u32string_view>;
  template<> struct hash<wstring_view>;
 
  inline namespace literals {
  inline namespace string_view_literals {
    // suffix for basic_string_view literals
    constexpr string_view    operator""sv(const char* str, size_t len) noexcept;
    constexpr u8string_view  operator""sv(const char8_t* str, size_t len) noexcept;
    constexpr u16string_view operator""sv(const char16_t* str, size_t len) noexcept;
    constexpr u32string_view operator""sv(const char32_t* str, size_t len) noexcept;
    constexpr wstring_view   operator""sv(const wchar_t* str, size_t len) noexcept;
  }
  }
}

Class template std::basic_string_view

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_string_view {
  public:
    // types
    using Traits_type            = Traits;
    using value_type             = CharT;
    using pointer                = value_type*;
    using const_pointer          = const value_type*;
    using reference              = value_type&;
    using const_reference        = const value_type&;
    using const_iterator         = /* implementation-defined */
    using iterator               = const_iterator;
    using const_reverse_iterator = reverse_iterator<const_iterator>;
    using reverse_iterator       = const_reverse_iterator;
    using size_type              = size_t;
    using difference_type        = ptrdiff_t;
    static constexpr size_type npos = size_type(-1);
 
    // construction and assignment
    constexpr basic_string_view() noexcept;
    constexpr basic_string_view(const basic_string_view&) noexcept = default;
    constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default;
    constexpr basic_string_view(const CharT* str);
    constexpr basic_string_view(nullptr_t) = delete;
    constexpr basic_string_view(const CharT* str, size_type len);
    template<class It, class End>
      constexpr basic_string_view(It begin, End end);
    template<class R>
      constexpr explicit basic_string_view(R&& r);
 
    // iterator support
    constexpr const_iterator begin() const noexcept;
    constexpr const_iterator end() const noexcept;
    constexpr const_iterator cbegin() const noexcept;
    constexpr const_iterator cend() const noexcept;
    constexpr const_reverse_iterator rbegin() const noexcept;
    constexpr const_reverse_iterator rend() const noexcept;
    constexpr const_reverse_iterator crbegin() const noexcept;
    constexpr const_reverse_iterator crend() const noexcept;
 
    // capacity
    constexpr size_type size() const noexcept;
    constexpr size_type length() const noexcept;
    constexpr size_type max_size() const noexcept;
    constexpr bool empty() const noexcept;
 
    // element access
    constexpr const_reference operator[](size_type pos) const;
    constexpr const_reference at(size_type pos) const;
    constexpr const_reference front() const;
    constexpr const_reference back() const;
    constexpr const_pointer data() const noexcept;
 
    // modifiers
    constexpr void remove_prefix(size_type n);
    constexpr void remove_suffix(size_type n);
    constexpr void swap(basic_string_view& s) noexcept;
 
    // string operations
    constexpr size_type copy(CharT* s, size_type n, size_type pos = 0) const;
 
    constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
 
    constexpr int compare(basic_string_view s) const noexcept;
    constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
    constexpr int compare(size_type pos1, size_type n1, basic_string_view s,
                          size_type pos2, size_type n2) const;
    constexpr int compare(const CharT* s) const;
    constexpr int compare(size_type pos1, size_type n1, const CharT* s) const;
    constexpr int compare(size_type pos1, size_type n1, const CharT* s,
                          size_type n2) const;
 
    constexpr bool starts_with(basic_string_view x) const noexcept;
    constexpr bool starts_with(CharT x) const noexcept;
    constexpr bool starts_with(const CharT* x) const;
    constexpr bool ends_with(basic_string_view x) const noexcept;
    constexpr bool ends_with(CharT x) const noexcept;
    constexpr bool ends_with(const CharT* x) const;
 
    constexpr bool contains(basic_string_view x) const noexcept;
    constexpr bool contains(CharT x) const noexcept;
    constexpr bool contains(const CharT* x) const;
 
    // searching
    constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
    constexpr size_type find(CharT c, size_type pos = 0) const noexcept;
    constexpr size_type find(const CharT* s, size_type pos, size_type n) const;
    constexpr size_type find(const CharT* s, size_type pos = 0) const;
    constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
    constexpr size_type rfind(CharT c, size_type pos = npos) const noexcept;
    constexpr size_type rfind(const CharT* s, size_type pos, size_type n) const;
    constexpr size_type rfind(const CharT* s, size_type pos = npos) const;
 
    constexpr size_type find_first_of(basic_string_view s,
                                      size_type pos = 0) const noexcept;
    constexpr size_type find_first_of(CharT c, size_type pos = 0) const noexcept;
    constexpr size_type find_first_of(const CharT* s, size_type pos, size_type n) const;
    constexpr size_type find_first_of(const CharT* s, size_type pos = 0) const;
    constexpr size_type find_last_of(basic_string_view s,
                                     size_type pos = npos) const noexcept;
    constexpr size_type find_last_of(CharT c, size_type pos = npos) const noexcept;
    constexpr size_type find_last_of(const CharT* s, size_type pos, size_type n) const;
    constexpr size_type find_last_of(const CharT* s, size_type pos = npos) const;
    constexpr size_type find_first_not_of(basic_string_view s,
                                          size_type pos = 0) const noexcept;
    constexpr size_type find_first_not_of(CharT c, size_type pos = 0) const noexcept;
    constexpr size_type find_first_not_of(const CharT* s, size_type pos,
                                          size_type n) const;
    constexpr size_type find_first_not_of(const CharT* s, size_type pos = 0) const;
    constexpr size_type find_last_not_of(basic_string_view s,
                                       size_type pos = npos) const noexcept;
    constexpr size_type find_last_not_of(CharT c, size_type pos = npos) const noexcept;
    constexpr size_type find_last_not_of(const CharT* s, size_type pos,
                                         size_type n) const;
    constexpr size_type find_last_not_of(const CharT* s, size_type pos = npos) const;
 
  private:
    const_pointer data_;          // exposition only
    size_type size_;              // exposition only
  };
 
  // deduction guides
  template<class It, class End>
    basic_string_view(It, End) -> basic_string_view<iter_value_t<It>>;
 
  template<class R>
    basic_string_view(R&&) -> basic_string_view<ranges::range_value_t<R>>;
}