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std::flat_map::at(3)	       C++ Standard Libary	    std::flat_map::at(3)

NAME
     std::flat_map::at - std::flat_map::at

Synopsis
	T& at( const Key& key );	     (1) (since C++23)
	const T& at( const Key& key ) const; (2) (since C++23)
	template< class K >		     (3) (since C++23)
	T& at( const K& x );
	template< class K >		     (4) (since C++23)
	const T& at( const K& x ) const;

	Returns  a  reference  to the mapped value of the element with specified
     key. If no
	such element exists, an exception of type std::out_of_range is thrown.

	1,2) The key is equivalent to key.
	3,4) The key compares equivalent to the value x. The  reference  to  the
     mapped value
	is obtained as if by expression this->find(x)->second.
	The  expression  this->find(x) must be well-formed and have well-defined
     behavior,
	otherwise the behavior is undefined.
	These overloads participate in overload resolution only  if  the  quali-
     fied-id
	Compare::is_transparent  is  valid and denotes a type. It allows calling
     this function
	without constructing an instance of Key.

Parameters
	key - the key of the element to find
	x   - a value of any type that can be transparently compared with a key

Return value
	A reference to the mapped value of the requested element.

Exceptions
	1,2) std::out_of_range if the container does not have  an  element  with
     the specified
	key.
	3,4) std::out_of_range if the container does not have the specified ele-
     ment, that
	is, if find(x) == end() is true.

Complexity
	Logarithmic in the size of the container.

Example
	 This section is incomplete
	 Reason: no example

See also
	operator[] access or insert specified element
		   (public member function)

Category:
	  * Todo no example

http://cppreference.com 	   2024.06.10		    std::flat_map::at(3)
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