[C++][STL] string documentation.

size() and length() function is equal.

http://en.cppreference.com/w/cpp/string/basic_string

std::basic_string

 

C++

 

Strings library

 

std::basic_string

 

Defined in header <string>
template<      class CharT,      class Traits = std::char_traits<CharT>,      class Allocator = std::allocator<CharT> > class basic_string;

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 tos[0] can be passed to functions that expect a pointer to the first element of a CharT[] array.

(since C++11)

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>

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	Unsigned integral type (usually std::size_t)
difference_type	Signed integer type (usually std::ptrdiff_t)
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)
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)
Iterators
begincbegin (C++11)	returns an iterator to the beginning  (public member function)
endcend (C++11)	returns an iterator to the end  (public member function)
rbegincrbegin (C++11)	returns a reverse iterator to the beginning  (public member function)
rendcrend (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)
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)