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

      From cppreference.com
      <cpp‎ |container‎ |list

      [edit template]
       
       
       
      std::list
      Member functions
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      (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.

      Ifempty() istrue, the behavior is undefined.

      		(until C++26)

      Ifempty() istrue:

      • If the implementation ishardened, acontract 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)

      Contents

      [edit]Return value

      Reference to the first element.

      [edit]Complexity

      Constant.

      [edit]Notes

      For a containerc, the expressionc.front() is equivalent to*c.begin().

      [edit]Example

      The following code usesfront to display the first element of astd::list<char>:

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

      [edit]See also

      access the last element
      (public member function)[edit]
      (C++11)
      		 returns a reverse iterator to the end
      (public member function)[edit]
      returns an iterator to the beginning
      (public member function)[edit]
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