check the existence of variable python

Question

if VAR in globals():
    print('TRUE')
else:
    print("FALSE")

I got this error:

  File "c:/Users/Admin/Desktop/Project_Nuôi_FB/te1.py", line 2, in <module>
    if VAR in globals():
NameError: name 'VAR' is not defined

How do I check the existence of a variable?

Answer 1

You have to enclose your VAR by quotes:

if 'VAR' in globals():
#  ^---^--- HERE

Answer 2

globals() return a dictionary with string keys. Thus to check if a variable named VAR is defined you need to do the following:

if 'VAR' in globals():
    print('TRUE')
else:
    print("FALSE")

Answer 3

You have to put quotation marks around variable name:

if 'VAR' in globals():
...

Answer 4

You can also use dir:

if 'VAR' in dir():
    print('TRUE')
else:
    print("FALSE")