New vs. Non-new Instantiation in C : What are the Key Differences?

Instantiation Differences: new vs. Non-new

This question explores the functional differences between instantiating an object using the new operator and instantiating it without new.

Non-new Instantiation

Time t(12, 0, 0); // t is a Time object

This instantiation creates a Time object named t that resides on the stack (in most implementations). It retains its existence within the current scope.

new Instantiation

Time *t = new Time(12, 0, 0); // t is a pointer to a dynamically allocated Time object

This instantiation allocates memory dynamically using operator new(), and then calls the constructor Time(). The address of the allocated memory block is stored in t. The Time object resides on the heap (typically). Later in the program, t must be deleted to release the allocated memory and prevent memory leaks.

Functional Differences

Besides the obvious difference in memory management, there are no substantial functional differences between the two instantiations. Both methods create instances of the Time class with the specified parameters.

N.B.

The terms "stack" and "heap" are generally used to indicate the storage locations of stack-allocated and heap-allocated objects, respectively. However, the C standard does not impose these distinctions based on memory locations. Instead, it categorizes objects based on their storage duration, which may or may not align with conventional concepts of stack and heap.

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