Scope of Variables in Python
Python variables are used to store the different type of data. We first need to assign a data to variable and then we can use inside anywhere in program.
Example of Python Variable
id=10908
name="Henry Fort"
salary=80000
print(id)
print(name)
print(salary)
10908
Henry Fort
80000
Scope of Variables
Scope variables decide the visibility of a variable in your program.
Global Scope Variables
Global variables are that defined outside the function and that are not specified to any function. These variable can be used in any part of the program.
Example of Global Scope Variable
def show():
print(s)
# Global scope
s = "Scope of Python Variables"
show() Scope of Python Variables
Example of Global Scope Variable with the same name of variable inside function
def show():
s = "Inside show() Function"
print(s)
# Global scope
s = "Scope of Python Variables"
show()
print(s)
Inside show() Function
Scope of Python Variables
Description of Output
Here when we call the show() function then the preference goes to the variable that is inside the function.
Local Scope Variables
Local variables are defined or declared inside the function block. These variables are not allowed to be used outside the function block or in global scope.
Example of Local Scope Variables
def show():
text = "Inside show() Function" #text is a local scope variable
print(text)
# Global scope
s = "Scope of Python Variables"
show()
print(text) #error in this line
Inside show() Function
Traceback (most recent call last):
File “E:/python/khusboo/test-py.py”, line 9, in
print(s1)
NameError: name ‘s1’ is not defined
Example to change the value of global variable inside the local scope
# Global scope
s = "Scope of Python Variables"
def show():
print(s)
# error in this line
s = "Inside show() Function"
print(s)
show()
print(s)
Traceback (most recent call last):
File “E:/python/khusboo/test-py.py”, line 9, in
show()
File “E:/python/khusboo/test-py.py”, line 5, in show
print(s)
UnboundLocalError: locaDesl variable ‘s’ referenced before assignment
Description of Output
In this example we can not change the value of global variable. When we try to change the value that line is assumed as the declaration of local variable inside the function. We can not use variable without creating it so the error will come at 5 line in program.
Example to change the value of global variable using the global keyword
By using the global keyword while changing the value of global variable inside the local scope of variable overcomes the problem that occurred in the last program.
# Global scope
text = "Scope of Python Variables"
def show():
global text
print(text)
text = "Inside show() Function"
print(text)
show()
print(text)
Scope of Python Variables
Inside show() Function
Inside show() Function
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