std::vector operator[]

since C++20

// prism-push-types:reference,const_reference,size_type
// Non const version
constexpr reference       operator[]( size_type pos );

// Const version
constexpr const_reference operator[]( size_type pos ) const;

until C++20

// prism-push-types:reference,const_reference,size_type
// Non const version
reference       operator[]( size_type pos );

// Const version
const_reference operator[]( size_type pos ) const;

Returns a reference

to the element at specified index pos.

caution

No bounds checking is performed.

Parameters

• pos - position of the element to return

Return value

Reference to the requested element.

Exceptions

(none)

Complexity

Constant - O(1).

Example

Main.cpp

#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