std::basic_string<CharT,Traits,Allocator>::operator[]

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical specifications

Symbols index

External libraries

 

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::contains (C++23) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23) 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 Deduction guides (C++17) 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>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversion stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) 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++17)(C++17)(C++17)(C++17)(C++20)

 

	(1)
reference operator[]( size_type pos );			(until C++20)
constexpr reference operator[]( size_type pos );			(since C++20)
		(2)
const_reference operator[]( size_type pos ) const;				(until C++20)
constexpr const_reference operator[]( size_type pos ) const;				(since C++20)

Returns a reference to the character at specified location pos. No bounds checking is performed. If pos > size(), the behavior is undefined.

1) If pos == size(), the behavior is undefined. 2) If pos == size(), a reference to the character with value CharT() (the null character) is returned.	(until C++11)
If pos == size(), a reference to the character with value CharT() (the null character) is returned. For the first (non-const) version, the behavior is undefined if this character is modified to any value other than CharT() .	(since C++11)

Parameters

pos

-

position of the character to return

Return value

Reference to the requested character.

Complexity

Constant.

Example

Run this code

#include <iostream>
#include <string>
 
int main()
{
    std::string const e("Exemplar");
    for (unsigned i = e.length() - 1; i != 0; i /= 2)
        std::cout << e[i];
    std::cout << '\n';
 
    const char* c = &e[0];
    std::cout << c << '\n'; // print as a C string
 
    //Change the last character of s into a 'y'
    std::string s("Exemplar ");
    s[s.size()-1] = 'y'; // equivalent to s.back() = 'y';
    std::cout << s << '\n';
}

Output:

rmx
Exemplar
Exemplary

See also

at	accesses the specified character with bounds checking (public member function)
front (C++11)	accesses the first character (public member function)
back (C++11)	accesses the last character (public member function)
operator[] (C++17)	accesses the specified character (public member function of std::basic_string_view<CharT,Traits>)