From cppreference.com
constexprconst_referenceat(size_typepos)const;(since C++17)Returns a const reference to the character at specified location pos. Bounds checking is performed, exception of type
will be thrown on invalid access.
Parameters
pos - position of the character to return Return value
Const reference to the requested character.
Exceptions
Throws
if pos>=size().
Complexity
Constant.
Example
Run this code
#include<iostream>#include<stdexcept>#include<string_view>intmain(){std::string_viewstr_view("abcdef");try{for(std::size_ti=0;true;++i)std::cout<<i<<": "<<str_view.at(i)<<'\n';}catch(conststd::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) See also
accesses the specified character
(public member function)
accesses the specified character with bounds checking
(public member function of std::basic_string<CharT,Traits,Allocator>)