


Constructor Limitations of std::array
Question:
Why doesn't std::array provide a constructor that initializes all elements with a specified value?
Answer:
By design, std::array is an aggregate type, which means it has no user-defined constructors. As a result, it cannot have a constructor like:
<code class="cpp">std::array<t size>::array(const T& value);</t></code>
Alternatives:
Although std::array lacks such a constructor, there are alternative options to achieve the same result:
-
Default Construction and std::fill: After default constructing an std::array, you can use the std::fill function to assign a specific value to all elements:
<code class="cpp">std::array<int> arr; std::fill(arr.begin(), arr.end(), -1);</int></code>
-
Trivial Initialization and std::uninitialized_fill: If the type contained within the std::array is trivially initializable, default construction won't initialize the memory to zero but will leave it uninitialized. In such cases, you can use std::uninitialized_fill to assign a specific value to all uninitialized elements:
<code class="cpp">std::array<:string> arr = {}; // Trivial initialization std::uninitialized_fill(arr.begin(), arr.end(), std::string("Example"));</:string></code>
By understanding the limitations of std::array's constructors and employing these alternatives, you can effectively initialize all elements of an std::array with a desired value.
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