TL;DR – Python global variables are declared outside a function and can be accessed anywhere in the code.
The difference between local and global variables in Python
In the example below, you can see two variables declared –
def f(): bit = "BitDegree" print (bit) f() bdg = "BitDegree" print (bdg)
While both have the same value assigned, they are declared and used differently:
bitis declared within the function. This makes it a local variable. Its scope is the body of the function – it cannot be used anywhere else.
bdgis declared outside of the function – this makes it global. You can use Python global variables anywhere in the code.
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How to use global variables in Python
When declaring global variables in Python, you can use the same names you have already used for local variables in the same code – this will not cause any issues because of the scope difference:
- If you use the variable within the function, it will prefer the local variable by default:
- If you use the variable anywhere else in the code, you will get the value of the global variable:
pizza = "Pepperoni" def f(): pizza = "Hawaii" print (pizza) f()
pizza = "Pepperoni" def f(): pizza = "Hawaii" print (pizza)
You can also create local variables by modifying previously defined Python global variables inside the function by using the keyword
bdg = 1000 def f(): global bdg bdg = bdg + 500
Python global variables: useful tips
- You can change the value of a Python global variable by simply assigning it a new value (redeclaring).
- To delete a variable, use the keyword
del. Trying to use a deleted variable will cause an error to fire.