How to Create Objects and Invoke Constructors Without Using `new` in C ?

Constructors and Malloc

Unlike new and delete expressions, std::malloc does not invoke the constructor upon allocating memory for an object. Therefore, to create an object while also calling its constructor, an alternative approach is required.

Possible Solutions:

1. Utilizing new:
This is the primary intended usage, as new explicitly creates an object and subsequently invokes its constructor.

Example:

<code class="cpp">A* a = new A();
delete a;</code>

2. Explicit Constructor Invocation (Placement New):
This method involves allocating memory using malloc and then manually invoking the constructor using placement new syntax.

Example:

<code class="cpp">A* a = (A*)malloc(sizeof(A));
new (a) A();

a->~A();
free(a);</code>

It is important to note that placement new requires the usage of the correct constructor overload and should be used sparingly. Generally, new should be employed for object creation, while placement new is suited for specific scenarios where memory management is handled manually.

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