std::string_view operator[]

od C++17

// Const version only
constexpr const_reference operator[]( size_type pos ) const;

Returns a reference

to the element at specified index pos.

uwaga

No bounds checking is performed, using an element out of bounds is undefined behavior

.

Parameters

• pos - position of the character to return

Return value

Reference to the requested character.

Exceptions

(none)

Complexity

Constant - O(1).

Notes

Unlike std::basic_string::operator[], std::basic_string_view::operator[](size()) has undefined behavior

instead of returning CharT().

Example

Main.cpp

#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