Variable scope in Python: Difference between revisions
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==Introduction== | ==Introduction== | ||
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A variable is similar to the memory functionality found in most calculators, in that it holds one value which can be retrieved many times, and that storing a new value erases the old. A variable differs from a calculator’s memory in that one can have many variables storing different values, and that each variable is referred to by name. <ref>http://python-textbok.readthedocs.org/en/1.0/Variables_and_Scope.html</ref> | A variable is similar to the memory functionality found in most calculators, in that it holds one value which can be retrieved many times, and that storing a new value erases the old. A variable differs from a calculator’s memory in that one can have many variables storing different values, and that each variable is referred to by name. <ref>http://python-textbok.readthedocs.org/en/1.0/Variables_and_Scope.html</ref> | ||
==Example | ==Example of variable scope in Python== | ||
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print(d) | print(d) | ||
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==References== | ==References== | ||
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[[Category:This information is incomplete]] | [[Category:This information is incomplete]] | ||
[[Category:Python]] | [[Category:Python]] | ||
[[Category: | [[Category:Variables]] | ||
[[Category:Scope]] | |||
Latest revision as of 09:46, 17 March 2016
This is basic programming knowledge [1]
Introduction[edit]
Recall that a variable is a label for a location in memory. It can be used to hold a value. In statically typed languages, variables have predetermined types, and a variable can only be used to hold values of that type. In Python, we may reuse the same variable to store values of any type.
A variable is similar to the memory functionality found in most calculators, in that it holds one value which can be retrieved many times, and that storing a new value erases the old. A variable differs from a calculator’s memory in that one can have many variables storing different values, and that each variable is referred to by name. [2]
Example of variable scope in Python[edit]
# This is a global variable
a = 0
if a == 0:
# This is still a global variable
b = 1
def my_function(c):
# this is a local variable
d = 3
print(c)
print(d)
# Now we call the function, passing the value 7 as the first and only parameter
my_function(7)
# a and b still exist
print(a)
print(b)
# c and d don't exist anymore -- these statements will give us name errors!
print(c)
print(d)