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

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[edit]

Strings library

Classes
basic_string
basic_string_view (C++17)
char_traits

[edit]

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)

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

Returns a const reference to the character at specified locationpos.

Ifpos< size() isfalse, the behavior is undefined.

(until C++26)

Ifpos< size() isfalse:

If the implementation ishardened, acontract 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)

[edit]Parameters

pos

position of the character to return

[edit]Return value

data_ [pos]

[edit]Exceptions

Does not throw.

[edit]Complexity

Constant.

[edit]Notes

Unlikestd::basic_string::operator[],std::basic_string_view::operator[](size()) does not return a reference toCharT().

[edit]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:

ey

[edit]See also

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