std::vector<T,Allocator>::operator[] (3) - Linux Manuals

std::vector<T,Allocator>::operator[]: std::vector<T,Allocator>::operator[]

NAME

std::vector<T,Allocator>::operator[] - std::vector<T,Allocator>::operator[]

Synopsis


reference operator[]( size_type pos );
const_reference operator[]( size_type pos ) const;


Returns a reference to the element at specified location pos. No bounds checking is performed.

Parameters


pos - position of the element to return

Return value


Reference to the requested element.

Complexity


Constant.

Notes


Unlike std::map::operator[], this operator never inserts a new element into the container.

Example


The following code uses operator[] to read from and write to a std::vector<int>:
// Run this code


  #include <vector>
  #include <iostream>


  int main()
  {
      std::vector<int> numbers {2, 4, 6, 8};


      std::cout << "Second element: " << numbers[1] << '\n';


      numbers[0] = 5;


      std::cout << "All numbers:";
      for (auto i : numbers) {
          std::cout << ' ' << i;
      }
      std::cout << '\n';
  }

Output:


  Second element: 4
  All numbers: 5 4 6 8

See also


   access specified element with bounds checking
at (public member function)

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