Python doesn’t have a block scope. If you come from a programming languages background like C, C++, or Java, In python there is no such thing called block scope.
What is block scope?
If a variable is declared inside an intended block of code like For loop, While loop, or condition flow (if else) The variable can only be accessed within a block
Python does not have a Block Scope check try the below examples
In Condition flow:
to_continue = True if to_continue: variable = "block scope" print(variable)
In While Loop:
while to_continue: variable = "block scope" print("Loop") to_continue=False print(variable)
Loop block scope
In For Loop:
for _ in range(5): variable = "block scope" print("Loop") print(variable)
Loop Loop Loop Loop Loop block scope
As we could see there is no block scope in Python, Variable can be accessed outside of the block except functions (Which is explained below)
Scope in Python
It’s essential to understand the scope of variables. It refers to the extent to which the variable is visible or accessible by the Python code.
In Python, The scope is determined by its indentation level. For example, A block of code within a function or a loop can only be accessible within that block and it will not be accessible outside of the block
Indentation in Python
Indentation is to add spaces at the beginning of a line of code to make sure that it is part of a block of code, especially In Python, indentation is essential and is used to define blocks of code such as loops, conditions, and functions
if x > 5: print("x is greater than 5") x = x + 1 print("x has been incremented")
There are 2 main types of scope in Python and it decides how to enable or restrict the use of variables across the program.
- Global Scope
- Local Scope
A variable declared in the program Will be made accessible across all parts of the program like within Loop, Condition Scope, functions, etc
global_variable = "testing" def my_function(): print ("Inside Function -> " + global_variable) my_function() print("Outside Function -> " + global_variable)
Inside Function -> testing Outside Function -> testing
The above example shows the global variable can be accessed from anywhere in the program
A variable declared inside a function will be restricted inside the function and can’t be accessible outside of it.
def my_function(): global_variable = "testing" print ("Inside Function -> " + global_variable) my_function()
Inside Function -> testing
In the above example, We could see the variable got declared inside the function will be accessed inside the function
def my_function(): global_variable = "testing" my_function() print("Outside Function -> " + global_variable)
Traceback (most recent call last): File "main.py", line 38, in <module> print("Outside Function -> " + global_variable) NameError: name 'global_variable' is not defined
Try accessing the variable declared inside the function will result in “NameError” as above.
"NameError: name 'global_variable' is not defined"
The above Error means the variable “global_variable” is unknown for this part of the program.
Hope the above blog helps to understand more about Scope & block scope in Python
Good Luck with your Learning