string::at
Return a character with bounds checking.
Synopsis
char&
at(
    std::size_t pos,
    boost::source_location const& loc = BOOST_CURRENT_LOCATION); (1)
char const&
at(
    std::size_t pos,
    boost::source_location const& loc = BOOST_CURRENT_LOCATION) const; (2)
Description
Returns a reference to the character specified at location pos.
Complexity
Constant.
Exception Safety
Strong guarantee.
Parameters
| Name | Description | 
|---|---|
  | 
A zero-based index to access.  | 
  | 
  | 
Exceptions
| Type | Thrown On | 
|---|---|
  | 
  | 
  | 
  |