Variable Shadowing in Python Last Updated : 06 Mar, 2024 Comments Improve Suggest changes Like Article Like Report In this article, we will understand the concept of variable shadowing in a Python programming language. To understand this concept, we need to be well versed with the scope of a lifetime of variables in python. Local variables:When we define a function, we can create variables that are scoped only to that function and are not accessible outside of the function. These variables are referred to as local variables ( as they are local to the function ) Python3 def fn(): # local variable a a = 3 print(a) # Error, variable a referenced before # assignment print(a) Hangup (SIGHUP)Traceback (most recent call last): File "Solution.py", line 10, in <module> print(a)NameError: name 'a' is not definedGlobal variables Variables are defined outside of any function and are potentially accessible anywhere in the program. Python3 # global variable a = 3 def fn(): # print 3 print(a) # print 3 print(a) fn() Output3 3 Note: For more information, refer to our Global and Local Variables in Python Variable shadowing occurs when a variable defined in the inner scope has the same name as a variable in the outer scope. Consider the example below, here the variable inside the function has the same name as a global variable. In this program, there are two versions of variable a, one which is defined globally and the other which is defined within the context of the function. Python treats these variables as completely separate variables. The global variable a is said to be shadowed by the local variable a. The way outer and inner variables with the same name are handled depends upon the name resolution rules of the language. Python3 # global variable a = 3 def fn(): # local variable a = 5 print(a) # prints 5 fn() print(a) # prints 3 Output5 3How to avoid variable shadowing?To modify a global variable, and avoid variable shadowing python provides global keyword which tells python to use the global version of the variable, instead of creating a new locally scoped variable. Python3 # global variable a = 3 def fn(): global a # global variable modified a = 5 print(a) # prints 5 print(a) # prints 3 fn() #function gets called after printing a which is 3 initially Output3 5To avoid variable shadowing at the function level, meaning if a variable in outer function has the same name as a variable in an inner function, python provides nonlocal keyword which tells python to use the variable defined in the outer function, instead of creating a new locally scoped variable Python3 def outer(): a = 5 def inner(): nonlocal a a = 3 print(a) # prints 3 inner() print(a) # prints 3 outer() Output3 3 Comment More infoAdvertise with us Next Article Variable Shadowing in Python M mostaptname Follow Improve Article Tags : Python python-basics Practice Tags : python Similar Reads Python Scope of Variables In Python, variables are the containers for storing data values. Unlike other languages like C/C++/JAVA, Python is not âstatically typedâ. 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