Difference between revisions of "CSC111 Exercises with Global Variables"

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(→‎Case)
(→‎Case 7)
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<source lang="text">
 
 
  >>>  
 
  >>>  
 
  <font color="red">Traceback (most recent call last):
 
  <font color="red">Traceback (most recent call last):
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     print( "f2", A )
 
     print( "f2", A )
 
  NameError: global name 'A' is not defined</font>
 
  NameError: global name 'A' is not defined</font>
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>>>
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|}
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<br />
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=Case  8=
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<br />
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{| class="wikitable" style="width:100%;"
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| style="width: 50%;" |
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<br />
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<source lang="python">
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def f1( x ):
 +
    global A
 +
    A = x
 +
 +
def f2( ):
 +
    global A
 +
    print( "f2", A )
 +
   
 +
f1( 10 )
 +
f2()
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</source>
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<br />
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|
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<source lang="text">
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>>>
 +
f2 10
 
  >>>  
 
  >>>  
 
</source>
 
</source>

Revision as of 18:33, 24 April 2014

--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 7



def f1( x ):
    A = x

def f2( ):
    print( "f2", A )
    
f1( 10 )
f2()



>>> 
Traceback (most recent call last):
 File "/Users/thiebaut/Desktop/PYTHON/globalExercises.py", line 9, in <module>
   f2()
 File "/Users/thiebaut/Desktop/PYTHON/globalExercises.py", line 6, in f2
   print( "f2", A )
NameError: global name 'A' is not defined
>>>



Case 8



def f1( x ):
    global A
    A = x

def f2( ):
    global A
    print( "f2", A )
    
f1( 10 )
f2()



 >>> 
f2 10
 >>>



















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