If a variable is declared inside a function, which statement correctly describes its scope and lifetime?

If a variable is declared inside a function, which statement correctly describes its scope and lifetime?

• A. Scope is the duration the variable exists in memory.
• B. Lifetime is the region of code where a variable is accessible.
• C. Both scope and lifetime refer to memory location.
• D. Scope is the region of code where a variable is accessible; lifetime is the duration the variable exists in memory.

Answer: (D)

Understanding the difference between where you can use a variable (scope) and how long it stays allocated in memory (lifetime) is the key idea. For a variable declared inside a function, its scope is the region of the code within that function where it can be accessed (the function body and any nested blocks after its declaration), nowhere outside the function. Its lifetime is the period during which memory for that variable exists, which for non-static local variables typically runs from when the function is entered until it returns. That combination—scope as the accessible region of code and lifetime as the duration the variable exists in memory—is why the statement is correct. The other descriptions mix up these terms or tie them to memory location in ways that aren’t accurate.

Understanding the difference between where you can use a variable (scope) and how long it stays allocated in memory (lifetime) is the key idea. For a variable declared inside a function, its scope is the region of the code within that function where it can be accessed (the function body and any nested blocks after its declaration), nowhere outside the function. Its lifetime is the period during which memory for that variable exists, which for non-static local variables typically runs from when the function is entered until it returns. That combination—scope as the accessible region of code and lifetime as the duration the variable exists in memory—is why the statement is correct. The other descriptions mix up these terms or tie them to memory location in ways that aren’t accurate.