CSC111 Exercises with Global Variables

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--D. Thiebaut (talk) 15:57, 24 April 2014 (EDT)


Explain the behavior of the different code sections shown below along with their output.

Case 1



A = 3

def f1( x ):
    print( "f1", x, A )

print( "A = ", A )
f1( 30 )



>>> 
A =  3
f1 30 3
>>>




Case 2



def f1( x ):
    print( "f1", x, A )

A = 3
print( "A = ", A )
f1( 30 )



>>> 
A =  3
f1 30 3
>>>


Case 3



A = 3

def f1( x ):
    print( "f1", x, A )
    A = 5
    
print( "A = ", A )
f1( 30 )
print( "A = ", A )



>>> 
A =  3
Traceback (most recent call last):
 File "/Users/thiebaut/Desktop/PYTHON/globalExercises.py", line 8, in <module>
   f1( 30 )
 File "/Users/thiebaut/Desktop/PYTHON/globalExercises.py", line 4, in f1
   print( "f1", x, A )
UnboundLocalError: local variable 'A' referenced before assignment

>>>


Case 4



A = 3

def f1( x ):
    global A
    print( "f1", x, A )
    A = 5
    
print( "A = ", A )
f1( 30 )
print( "A = ", A )



>>> 
A =  3
f1 30 3
A =  5
>>>


Case 5



def f1( x ):
    A = []    
    print( "f1", x, A )
    A.append( 10 )
    A.append( 20 )
    print( "f1", x, A )

A = [1, 2, 3]
print( "A = ", A )
f1( 30 )
print( "A = ", A )



>>> 
A =  [1, 2, 3]
f1 30 []
f1 30 [10, 20]
A =  [1, 2, 3]
>>>


Case 6



def f1( x ):
    global A
    A = []    
    print( "f1", x, A )
    A.append( 10 )
    A.append( 20 )
    print( "f1", x, A )

A = [1, 2, 3]
print( "A = ", A )
f1( 30 )
print( "A = ", A )



>>> 
A =  [1, 2, 3]
f1 30 []
f1 30 [10, 20]
A =  [10, 20]

>>>


Case







>>> 


>>>



















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