How to check whether a str(variable) is empty or not?

Question

How do I make a:

if str(variable) == [contains text]:

condition?

(or something, because I am pretty sure that what I just wrote is completely wrong)

I am sort of trying to check if a random.choice from my list is ["",] (blank) or contains ["text",].

Answer 1

You could just compare your string to the empty string:

if variable != "":
    etc.

But you can abbreviate that as follows:

if variable:
    etc.

Explanation: An if actually works by computing a value for the logical expression you give it: True or False. If you simply use a variable name (or a literal string like "hello") instead of a logical test, the rule is: An empty string counts as False, all other strings count as True. Empty lists and the number zero also count as false, and most other things count as true.

Answer 2

The "Pythonic" way to check if a string is empty is:

import random
variable = random.choice(l)
if variable:
    # got a non-empty string
else:
    # got an empty string

Answer 3

Just say if s or if not s. As in

s = ''
if not s:
    print 'not', s

So in your specific example, if I understand it correctly...

>>> import random
>>> l = ['', 'foo', '', 'bar']
>>> def default_str(l):
...     s = random.choice(l)
...     if not s:
...         print 'default'
...     else:
...         print s
... 
>>> default_str(l)
default
>>> default_str(l)
default
>>> default_str(l)
bar
>>> default_str(l)
default

Answer 4

Empty strings are False by default:

>>> if not "":
...     print("empty")
...
empty

Answer 5

Some time we have more spaces in between quotes, then use this approach

a = "   "
>>> bool(a)
True
>>> bool(a.strip())
False

if not a.strip():
    print("String is empty")
else:
    print("String is not empty")

Answer 6

For python 3, you can use bool()

>>> bool(None)
False
>>> bool("")
False
>>> bool("a")
True
>>> bool("ab")
True
>>> bool("9")
True

Answer 7

element = random.choice(myList)
if element:
    # element contains text
else:
    # element is empty ''

Answer 8

How do i make an: if str(variable) == [contains text]: condition?

Perhaps the most direct way is:

if str(variable) != '':
  # ...

Note that the if not ... solutions test the opposite condition.

Answer 9

if the variable contains text then:

len(variable) != 0

of it does not

len(variable) == 0

Answer 10

string = "TEST"
try:
  if str(string):
     print "good string"
except NameError:
     print "bad string"

Answer 11

use "not" in if-else

x = input()

if not x:
   print("Value is not entered")
else:
   print("Value is entered")

Answer 12

{
test_str1 = "" 
test_str2 = "  "
  
# checking if string is empty 
print ("The zero length string without spaces is empty ? : ", end = "") 
if(len(test_str1) == 0): 
    print ("Yes") 
else : 
    print ("No") 
  
# prints No  
print ("The zero length string with just spaces is empty ? : ", end = "") 
if(len(test_str2) == 0): 
    print ("Yes") 
else : 
    print ("No") 
}

Answer 13

Python strings are immutable and hence have more complex handling when talking about its operations. Note that a string with spaces is actually an empty string but has a non-zero size. Let’s see two different methods of checking if string is empty or not: Method #1 : Using Len() Using Len() is the most generic method to check for zero-length string. Even though it ignores the fact that a string with just spaces also should be practically considered as an empty string even its non-zero.

Method #2 : Using not

Not operator can also perform the task similar to Len(), and checks for 0 length string, but same as the above, it considers the string with just spaces also to be non-empty, which should not practically be true.

Good Luck!

Answer 14

#empty variable
myvar = ""

#check if variable is empty
if not myvar:
    print("variable is empty") # variable is empty