std::basic_string_view<CharT,Traits>::operator[]

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Strings library

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string_view

Member functions basic_string_view::basic_string_view    basic_string_view::operator= Iterators basic_string_view::beginbasic_string_view::cbegin basic_string_view::endbasic_string_view::cend basic_string_view::rbeginbasic_string_view::crbegin basic_string_view::rendbasic_string_view::crend Capacity basic_string_view::sizebasic_string_view::length basic_string_view::max_size basic_string_view::empty Operations basic_string_view::copy basic_string_view::substr basic_string_view::compare basic_string_view::starts_with (C++20) basic_string_view::ends_with (C++20) basic_string_view::contains (C++23) basic_string_view::find basic_string_view::rfind basic_string_view::find_first_of basic_string_view::find_last_of basic_string_view::find_first_not_of basic_string_view::find_last_not_of

Element access basic_string_view::at basic_string_view::operator[] basic_string_view::front basic_string_view::back basic_string_view::data Modifiers basic_string_view::remove_prefix basic_string_view::remove_suffix basic_string_view::swap Constants basic_string_view::npos Non-member functions operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) operator<< operator""sv Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u8string_view>hash<std::u16string_view>hash<std::u32string_view> (C++20) Deduction guides (C++20)

 

constexpr const_reference operator[]( size_type pos ) const;		(since C++17)

Returns a const reference to the character at specified location pos.

If pos < size() is false, the behavior is undefined.	(until C++26)
If pos < size() is false: If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under “observe” evaluation semantic, the behavior is undefined. If the implementation is not hardened, the behavior is undefined.	(since C++26)

Parameters

pos

-

position of the character to return

Return value

data_ [pos]

Exceptions

Does not throw.

Complexity

Constant.

Notes

Unlike std::basic_string::operator[], std::basic_string_view::operator[](size() does not return a reference to CharT().

Example

Run this code

#include <iostream>
#include <string_view>
 
int main()
{
    std::string str = "Exemplar";
    std::string_view v = str;
    std::cout << v[2] << '\n';
/  v[2] = 'y'; / Error: cannot modify through a string view
    str[2] = 'y';
    std::cout << v[2] << '\n';
}

Output:

e
y

See also

at	accesses the specified character with bounds checking (public member function)
operator[]	accesses the specified character (public member function of std::basic_string<CharT,Traits,Allocator>)

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