I am matching an empty value with an array element which has one value in it and the array does not have any empty values. However, still this script works.
import re
b = ""
links_check_arr = ['Arunsdsdds']
for links_find in links_check_arr:
if b in links_find:
print links_find
print b
How come it is working when b is empty and the array element is 'Arunsdsdds' (which has no empty value in it)?
An empty string is always considered to be part of any string:
>>> "" in "abcd"
True
The empty string is a substring of every string in Python. This is because the substring of length 0 of any string s[0:0] is equal to the empty string.
A proper way to check if a string s is not empty is simply if not s:, as empty strings are "falsey".
To check if something is equal to the empty string, just use == as opposed to in.
tristan gives a detailed answer in the post Why Python returns True when checking if an empty string is in another?. The important sentence is there:
Empty strings are always considered to be a substring of any other string, so "" in "abc" will return True.
You find this sentence in the Python 2.7. reference, article Expressions in the chapter Comparisons. Or for Python 3 in Expressions, chapter Membership test operations.
==instead ofin.