std::list<T,Allocator>::front

 

C++

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std::list

Member functions
list::list list::~list list::operator= list::assign list::assign_range (C++23)   list::get_allocator Element access list::front list::back Iterators list::beginlist::cbegin (C++11) list::endlist::cend (C++11) list::rbeginlist::crbegin (C++11) list::rendlist::crend (C++11) Capacity list::size list::empty list::max_size	Modifiers list::clear list::insert list::insert_range (C++23) list::emplace (C++11) list::erase list::push_front list::emplace_front (C++11) list::prepend_range (C++23) list::pop_front list::push_back list::emplace_back (C++11) list::append_range (C++23) list::pop_back list::resize list::swap Operations list::merge list::splice list::removelist::remove_if list::reverse list::unique list::sort
Non-member functions
operator==operator<=> (C++20) swap(std::list) erase(std::list)erase_if(std::list) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)

 

reference front();	(1)	(constexpr since C++26)
const_reference front() const;	(2)	(constexpr since C++26)

Returns a reference to the first element in the container.

If empty() is true, the behavior is undefined.	(until C++26)
If empty() is true: If the implementation is hardened, a contract violation occurs. Moreover, if the contract-violation handler returns under “observe” evaluation semantic, the behavior is undefined. If the implementation is not hardened, the behavior is undefined.	(since C++26)

Return value

Reference to the first element.

Complexity

Constant.

Notes

For a container c, the expression c.front() is equivalent to *c.begin().

Example

The following code uses front to display the first element of a std::list<char>:

Run this code

#include <cassert>
#include <list>
 
int main()
{
    std::list<char> letters{'a', 'b', 'c', 'd'};
    assert(letters.front() == 'a');
}

See also

back	access the last element (public member function)
rendcrend (C++11)	returns a reverse iterator to the end (public member function)
begincbegin (C++11)	returns an iterator to the beginning (public member function)

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