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/C++

std::basic_string_view<CharT,Traits>::at

constexpr const_reference at( size_type pos ) const;

(since C++17)

Returns a const reference to the character at specified location pos. Bounds checking is performed, exception of type std::out_of_range will be thrown on invalid access.

Parameters

pos

position of the character to return

Return value

Const reference to the requested character.

Exceptions

Throws std::out_of_range if pos >= size().

Complexity

Constant.

Example

#include <iostream>
#include <stdexcept>
#include <string_view>
 
int main()
{
    std::string_view str_view("abcdef");
 
    try
    {
        for (std::size_t i = 0; true; ++i)
            std::cout << i << ": " << str_view.at(i) << '\n';
    }
    catch (const std::out_of_range& e)
    {
        std::cout << "Whooops. Index is out of range.\n";
        std::cout << e.what() << '\n';
    }
}

Possible output:

0: a
1: b
2: c
3: d
4: e
5: f
6: Whooops. Index is out of range.
basic_string_view::at: __pos (which is 6) >= this->size() (which is 6)