Question

Predict the output of the given code snippet.

ptr=40
def result():
     print ptr
     ptr=90
def func(var):
     if var<=60:
     ptr=30
     print ptr
result()
func(60)
func(70)

Answer 1

Trace:

• Inside result(), the statement ptr = 90 makes ptr a local variable throughout that function.
• Therefore, print(ptr) tries to use the local ptr before it has been assigned a value.
• The program stops at result(); neither func(60) nor func(70) executes.

UnboundLocalError: cannot access local variable 'ptr' where it is not associated with a value

To modify the global ptr, write global ptr inside result() before assigning to it.