std::unique_ptr$lt;T,Deleter>::operator[]

Since C++11

T& operator[]( std::size_t i ) const;

Since C++23

T& operator[]( std::size_t i ) constexpr;

operator[] provides access to elements of an array managed by a unique_ptr.

The parameter i shall be less than the number of elements in the array; otherwise, the behavior is undefined.

This member function is only provided for specializations for array types.

Parameters

i - the index of the element to be returned

Return value

Returns the element at index i, i.e. get()[i].

Example

#include <iostream>
#include <memory>
 
int main() 
{
    const int size = 10; 
    std::unique_ptr<int[]> fact(new int[size]);
 
    for (int i = 0; i < size; ++i) {
        fact[i] = (i == 0) ? 1 : i * fact[i-1];
    }
 
    for (int i = 0; i < size; ++i) {
        std::cout 
            << i << "! = " 
            << fact[i] << '\n';
    }
}

Result

0! = 1
1! = 1
2! = 2
3! = 6
4! = 24
5! = 120
6! = 720
7! = 5040
8! = 40320
9! = 362880