How To Define Global Variable In Python

Defining a global variable in Python can be useful in multiple scenarios. A global variable is a variable that can be accessed from any part of the code. In this tutorial, we will go through the steps of defining a global variable in Python.

Steps to Define Global Variable in Python:

1. To define a global variable in Python, you need to use the keyword global followed by the name of the variable.

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global_var = 10
 
def function():
    global global_var
 
global_var += 1
print(global_var)
 
function()

output:

11

2. In the above example, we have defined a global variable global_var and assigned it a value of 10. We then created a function which uses the global keyword to access the global_var variable and increment it by 1. Finally, we called the function and printed the value of the global_var variable.

3. It is important to note that you must use the global keyword in any function that accesses the global variable. If you do not use the global keyword, Python will create a new local variable with the same name as the global variable.

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global_var = 10
 
def function():
    global_var += 1
 
print(global_var)
 
function()

output:

10
UnboundLocalError: cannot access local variable 'global_var' where it is not associated with a value

4. In the above example, we have removed the global keyword from the function. When we call the function, Python will try to create a new local variable called global_var which conflicts with the name of the global variable. This results in an error.

5. Global variables can also be defined outside of functions.

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global_var = 10
 
def function():
    print(global_var)
 
function()

output:

10

6. In the above example, we define the global_var variable outside of any functions. We then create a function that simply prints the value of the global_var variable.

7. It is important to note that using global variables can make it difficult to understand and debug code. If possible, it is recommended to use local variables instead of global variables.

Conclusion

Defining a global variable in Python is easy. You just need to use the global keyword followed by the name of the variable. However, using global variables can make your code difficult to read and debug. If possible, it is recommended to use local variables instead.