How to check whether a variable exists in Python

Learn, how to check whether a variable exists or not in Python.

Checking global variable

To check if a global variable exists or not in Python, we can use the built-in globals() function.

Example:

fruit = "apple"

if 'fruit' in globals():
   print ("fruit variable exist")
else:
    print ("fruit variable does not exist")

Output:

"fruit variable exist"

The globals() function returns a dictionary containing the variables that are defined inside the global namespace.

Checking local variable

To check if a local variable exists or not, we can use the built-in locals() function.

Example:

def name():
    a = "Hello" # a is a local variable

    if 'a' in locals():
       print ('a variable exist')
    else:
        print ('a variable does not exist')

name()

Output:

"a variable exist"

The locals() function returns a dictionary containing the variables that are defined inside the local namespace.