std::basic_string_view<CharT,Traits>::operator[] - cppreference.com

From cppreference.com

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.
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

#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:

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