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Python: eval() function

eval() function

The eval() function is used to evaluate the specified expression. If the expression is a correct Python statement, it will be executed.

Version:

(Python 3)

Syntax:

eval(expression, globals=None, locals=None)

Parameter:

Name Description Required /
Optional
expression A string as parsed that will evaluated as a Python expression. Required
globals A dictionary Optional
locals A mapping object. Optional

Example: Python eval() function

x = 5
print(eval('x+1'))
print(eval('x'))

Output:

6
5

Example: Passing empty dictionary as globals parameter

from math import *
print(eval('dir()', {}))

#Following code will raise an exception
print(eval('sqrt(36)', {}))

Output:

['__builtins__']
Traceback (most recent call last):
  File "/tmp/sessions/5cb89b87138fc37f/main.py", line 5, in 
    print(eval('sqrt(36)', {}))
  File "", line 1, in 
NameError: name 'sqrt' is not defined

Python Code Editor:

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Python: Tips of the Day

How do I check if a list is empty?

For example, if passed the following:

a = []
if not a:
  print("List is empty")

Ref: https://bit.ly/2A4JXx9