std::basic_string

 

C++

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Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

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Numerics library

Input/output library

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Regular expressions library (C++11)

Atomic operations library (C++11)

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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

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str basic_string::operator basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)

Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::swap Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Constants basic_string::npos

Non-member functions operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>= Numeric conversion (C++11) stoistolstoll stoulstoull stofstodstold to_string to_wstring Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string>hash<std::u8string> (C++11)(C++11)(C++11)(C++11)(C++20) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string>hash<std::pmr::u8string> (C++20)(C++20)(C++20)(C++20)(C++20) Deduction guides(C++17)

 

Defined in header <string>
template<     class CharT,     class Traits = std::char_traits<CharT>,     class Allocator = std::allocator<CharT> > class basic_string;	(1)
namespace pmr {     template <class CharT, class Traits = std::char_traits<CharT>>     using basic_string = std::basic_string< CharT, Traits,                                             std::polymorphic_allocator<CharT>> }	(2)	(since C++17)

The class template basic_string stores and manipulates sequences of char-like objects, which are non-array objects of trivial standard-layout type. The class is dependent neither on the character type nor on the nature of operations on that type. The definitions of the operations are supplied via the Traits template parameter - a specialization of std::char_traits or a compatible traits class. Traits::char_type and CharT must name the same type; otherwise the program is ill-formed.

The elements of a basic_string are stored contiguously, that is, for a basic_string s, &*(s.begin() + n) == &*s.begin() + n for any n in [0, s.size()), or, equivalently, a pointer to s[0] can be passed to functions that expect a pointer to the first element of a CharT[] array.

(since C++11)

std::basic_string satisfies the requirements of AllocatorAwareContainer, SequenceContainer and ContiguousContainer (since C++17)

Several typedefs for common character types are provided:

Defined in header <string>
Type	Definition
std::string	std::basic_string<char>
std::wstring	std::basic_string<wchar_t>
std::u8string (C++20)	std::basic_string<char8_t>
std::u16string (C++11)	std::basic_string<char16_t>
std::u32string (C++11)	std::basic_string<char32_t>
std::pmr::string (C++17)	std::pmr::basic_string<char>
std::pmr::wstring (C++17)	std::pmr::basic_string<wchar_t>
std::pmr::u8string (C++20)	std::pmr::basic_string<char8_t>
std::pmr::u16string (C++17)	std::pmr::basic_string<char16_t>
std::pmr::u32string (C++17)	std::pmr::basic_string<char32_t>

Template parameters

CharT	-	character type
Traits	-	traits class specifying the operations on the character type
Allocator	-	Allocator type used to allocate internal storage

Member types

Member type	Definition
traits_type	Traits
value_type	CharT
allocator_type	Allocator
size_type	Allocator::size_type (until C++11) std::allocator_traits<Allocator>::size_type (since C++11)
difference_type	Allocator::difference_type (until C++11) std::allocator_traits<Allocator>::difference_type (since C++11)
reference	Allocator::reference (until C++11) value_type& (since C++11)
const_reference	Allocator::const_reference (until C++11) const value_type& (since C++11)
pointer	Allocator::pointer (until C++11) std::allocator_traits<Allocator>::pointer (since C++11)
const_pointer	Allocator::const_pointer (until C++11) std::allocator_traits<Allocator>::const_pointer (since C++11)
iterator	LegacyRandomAccessIterator
const_iterator	Constant LegacyRandomAccessIterator
reverse_iterator	std::reverse_iterator<iterator>
const_reverse_iterator	std::reverse_iterator<const_iterator>

Member functions

(constructor)	constructs a basic_string (public member function)
(destructor)	destroys the string, deallocating internal storage if used (public member function)
operator=	assigns values to the string (public member function)
assign	assign characters to a string (public member function)
get_allocator	returns the associated allocator (public member function)
Element access
at	accesses the specified character with bounds checking (public member function)
operator[]	accesses the specified character (public member function)
front (C++11)	accesses the first character (public member function)
back (C++11)	accesses the last character (public member function)
data	returns a pointer to the first character of a string (public member function)
c_str	returns a non-modifiable standard C character array version of the string (public member function)
operator basic_string_view (C++17)	returns a non-modifiable string_view into the entire string (public member function)
Iterators
begincbegin (C++11)	returns an iterator to the beginning (public member function)
end cend (C++11)	returns an iterator to the end (public member function)
rbegin crbegin (C++11)	returns a reverse iterator to the beginning (public member function)
rend crend (C++11)	returns a reverse iterator to the end (public member function)
Capacity
empty	checks whether the string is empty (public member function)
sizelength	returns the number of characters (public member function)
max_size	returns the maximum number of characters (public member function)
reserve	reserves storage (public member function)
capacity	returns the number of characters that can be held in currently allocated storage (public member function)
shrink_to_fit (C++11)	reduces memory usage by freeing unused memory (public member function)
Operations
clear	clears the contents (public member function)
insert	inserts characters (public member function)
erase	removes characters (public member function)
push_back	appends a character to the end (public member function)
pop_back (C++11)	removes the last character (public member function)
append	appends characters to the end (public member function)
operator+=	appends characters to the end (public member function)
compare	compares two strings (public member function)
starts_with (C++20)	checks if the string starts with the given prefix (public member function)
ends_with (C++20)	checks if the string ends with the given suffix (public member function)
replace	replaces specified portion of a string (public member function)
substr	returns a substring (public member function)
copy	copies characters (public member function)
resize	changes the number of characters stored (public member function)
swap	swaps the contents (public member function)
Search
find	find characters in the string (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_first_not_of	find first absence of characters (public member function)
find_last_of	find last occurrence 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+	concatenates two strings or a string and a char (function template)
operator==operator!=operator<operator>operator<=operator>=	lexicographically compares two strings (function template)
std::swap(std::basic_string)	specializes the std::swap algorithm (function template)
erase(std::basic_string)erase_if(std::basic_string) (C++20)	Erases all elements satisfying specific criteria (function template)
Input/output
operator<<operator>>	performs stream input and output on strings (function template)
getline	read data from an I/O stream into a string (function template)
Numeric conversions
stoistolstoll (C++11)(C++11)(C++11)	converts a string to a signed integer (function)
stoulstoull (C++11)(C++11)	converts a string to an unsigned integer (function)
stofstodstold (C++11)(C++11)(C++11)	converts a string to a floating point value (function)
to_string (C++11)	converts an integral or floating point value to string (function)
to_wstring (C++11)	converts an integral or floating point value to wstring (function)

Literals

Defined in inline namespace std::literals::string_literals
operator""s (C++14)	Converts a character array literal to basic_string (function)

Helper classes

std::hash<std::string>std::hash<std::u8string>std::hash<std::u16string>std::hash<std::u32string>std::hash<std::wstring>std::hash<std::pmr::string>std::hash<std::pmr::u8string>std::hash<std::pmr::u16string>std::hash<std::pmr::u32string>std::hash<std::pmr::wstring> (C++11)(C++20)(C++11)(C++11)(C++11)(C++20)(C++20)(C++20)(C++20)(C++20)

hash support for strings (class template specialization)