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std::basic_string

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)

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. 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.

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::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::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 Traits::char_type

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 RandomAccessIterator

const_iterator Constant random access iterator

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	access specified character with bounds checking (public member function)
operator[]	access 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)
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)
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::u16string>std::hash<std::u32string>std::hash<std::wstring>

(C++11)(C++11)(C++11)(C++11)

hash support for strings
(class template specialization)

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std::basic_string

Template parameters

Member types

Member functions

Element access

Iterators

Capacity

Operations

Search

Constants

Non-member functions

Input/output

Numeric conversions

Literals

Helper classes