Difference between revisions of "CSC111 Exercises with Global Variables"
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--[[User:Thiebaut|D. Thiebaut]] ([[User talk:Thiebaut|talk]]) 15:57, 24 April 2014 (EDT) | --[[User:Thiebaut|D. Thiebaut]] ([[User talk:Thiebaut|talk]]) 15:57, 24 April 2014 (EDT) | ||
---- | ---- | ||
| + | <br /> | ||
| + | Explain the behavior of the different code sections shown below along with their output. | ||
<br /> | <br /> | ||
=Case 1= | =Case 1= | ||
| Line 20: | Line 22: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| − | A = 3 | + | A = 3 |
| − | f1 30 3 | + | f1 30 3 |
| − | >>> | + | >>> |
</source> | </source> | ||
|} | |} | ||
| Line 48: | Line 50: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| − | A = 3 | + | A = 3 |
| − | f1 30 3 | + | f1 30 3 |
| − | >>> | + | >>> |
</source> | </source> | ||
|} | |} | ||
| Line 92: | Line 94: | ||
<br /> | <br /> | ||
| − | =Case | + | =Case 4 = |
<br /> | <br /> | ||
{| class="wikitable" style="width:100%;" | {| class="wikitable" style="width:100%;" | ||
| Line 98: | Line 100: | ||
<br /> | <br /> | ||
<source lang="python"> | <source lang="python"> | ||
| − | + | A = 3 | |
| + | |||
| + | def f1( x ): | ||
| + | global A | ||
| + | print( "f1", x, A ) | ||
| + | A = 5 | ||
| + | |||
| + | print( "A = ", A ) | ||
| + | f1( 30 ) | ||
| + | print( "A = ", A ) | ||
| + | |||
</source> | </source> | ||
| Line 104: | Line 116: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| − | + | A = 3 | |
| − | + | f1 30 3 | |
| − | >>> | + | A = 5 |
| + | >>> | ||
</source> | </source> | ||
|} | |} | ||
| Line 113: | Line 126: | ||
<!-- ---------------------------------------------------------------------------------------------- --> | <!-- ---------------------------------------------------------------------------------------------- --> | ||
<br /> | <br /> | ||
| − | =Case = | + | |
| + | =Case 5= | ||
<br /> | <br /> | ||
{| class="wikitable" style="width:100%;" | {| class="wikitable" style="width:100%;" | ||
| Line 119: | Line 133: | ||
<br /> | <br /> | ||
<source lang="python"> | <source lang="python"> | ||
| − | + | 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 ) | ||
| + | |||
</source> | </source> | ||
| Line 125: | Line 150: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| − | + | A = [1, 2, 3] | |
| − | + | f1 30 [] | |
| − | >>> | + | f1 30 [10, 20] |
| + | A = [1, 2, 3] | ||
| + | >>> | ||
</source> | </source> | ||
|} | |} | ||
| Line 134: | Line 161: | ||
<!-- ---------------------------------------------------------------------------------------------- --> | <!-- ---------------------------------------------------------------------------------------------- --> | ||
<br /> | <br /> | ||
| − | =Case = | + | |
| + | =Case 6= | ||
<br /> | <br /> | ||
{| class="wikitable" style="width:100%;" | {| class="wikitable" style="width:100%;" | ||
| Line 140: | Line 168: | ||
<br /> | <br /> | ||
<source lang="python"> | <source lang="python"> | ||
| − | + | ||
| + | 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 ) | ||
| + | |||
</source> | </source> | ||
| Line 146: | Line 187: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| + | A = [1, 2, 3] | ||
| + | f1 30 [] | ||
| + | f1 30 [10, 20] | ||
| + | A = [10, 20] | ||
| + | >>> | ||
| + | </source> | ||
| + | |} | ||
| + | |||
| + | <!-- ---------------------------------------------------------------------------------------------- --> | ||
| + | <br /> | ||
| + | |||
| + | =Case 7= | ||
| + | <br /> | ||
| + | {| class="wikitable" style="width:100%;" | ||
| + | | style="width: 50%;" | | ||
| + | <br /> | ||
| + | <source lang="python"> | ||
| + | def f1( x ): | ||
| + | A = x | ||
| + | |||
| + | def f2( ): | ||
| + | print( "f2", A ) | ||
| + | |||
| + | f1( 10 ) | ||
| + | f2() | ||
| − | |||
</source> | </source> | ||
| + | <br /> | ||
| + | | | ||
| + | >>> | ||
| + | <font color="red">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</font> | ||
| + | >>> | ||
|} | |} | ||
| − | + | ||
<br /> | <br /> | ||
| − | =Case = | + | =Case 8= |
<br /> | <br /> | ||
{| class="wikitable" style="width:100%;" | {| class="wikitable" style="width:100%;" | ||
| Line 161: | Line 236: | ||
<br /> | <br /> | ||
<source lang="python"> | <source lang="python"> | ||
| − | + | def f1( x ): | |
| + | global A | ||
| + | A = x | ||
| + | |||
| + | def f2( ): | ||
| + | global A | ||
| + | print( "f2", A ) | ||
| + | |||
| + | f1( 10 ) | ||
| + | f2() | ||
</source> | </source> | ||
| Line 167: | Line 251: | ||
| | | | ||
<source lang="text"> | <source lang="text"> | ||
| − | >>> | + | >>> |
| − | + | f2 10 | |
| − | + | >>> | |
| − | >>> | ||
</source> | </source> | ||
|} | |} | ||
Latest revision as of 18:34, 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
>>>
|
