Which statement best describes defining a variable?

• A. Assigning to a variable updates the variable's value.
• B. Defining a variable creates a function.
• C. Definition assigns memory to a variable to be used later.
• D. Assigning a value creates memory for a new variable.

Answer: (C)

Defining a variable means reserving a storage location in memory for that variable and giving it a name (and typically a type). This allocation happens so that there is a place in memory ready to hold a value later. That’s why the statement describing defining a variable is that memory is assigned to a variable to be used later. Once the storage exists, you can assign a value to it, which simply writes into that pre-allocated space. Assigning updates the value stored, but does not create the storage itself. Creating a function is not about variable storage, and saying that assigning creates memory for a new variable isn’t accurate because the memory is allocated at definition, not at assignment. For example, in many languages you’d see something like an int x; which defines and allocates space for x, and then x = 5; which assigns a value to that space.