Variable Scope and the `global` keyword Flashcards

What is the output? def f(): global z z = 99 f() print(z)

Answer: 99

f() creates global z = 99, so it is accessible at module level after the call.

Which of the following statements about variable shadowing is TRUE?

Answer: A local variable with the same name as a global variable hides the global inside that function

Shadowing means the local name takes precedence inside the function; the global is unaffected.

What is printed? a = 1 def outer(): a = 2 def inner(): a = 3 print(a) inner() print(a) outer() print(a)

Answer: 3 2 1

Each function has its own local a; inner prints 3, outer prints 2, module level prints 1.

Which built-in function lets you inspect the global namespace dictionary?

Answer: globals()

globals() returns a dictionary of the current module's global namespace.

What is the result of the following code? x = 'outside' def test(): global x del x test() print(x)

Answer: NameError

del x with global x deletes the module-level variable, so print(x) raises NameError.

At what point does Python decide whether a variable name inside a function is local or global?

Answer: At compile time (when the function is defined), based on whether an assignment exists in the function body

Python's compiler scans the function body; if any assignment to a name exists (without global), it is marked local for the entire function.

What does the following code demonstrate? pi = 3.14 def area(r): return pi * r * r print(area(2))

Answer: A function reading a global variable without the global keyword (read-only access)

Functions can read global variables freely; global is only required when you want to rebind (assign to) the name inside the function.