Check if string contains only whitespace

Question

How can I test if a string contains only whitespace?

Example strings:

" " (space, space, space)
" t n " (space, tab, space, newline, space)
"nnntn" (newline, newline, newline, tab, newline)

Asked By: bodacydo

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Source

Answer 1

Use the str.isspace() method:

Return True if there are only whitespace characters in the string and there is at least one character, False otherwise.

A character is whitespace if in the Unicode character database (see unicodedata), either its general category is Zs (“Separator, space”), or its bidirectional class is one of WS, B, or S.

Combine that with a special case for handling the empty string.

Alternatively, you could use str.strip() and check if the result is empty.

Answered By: Vladislav

Answer 2

You can use the str.isspace() method.

Answered By: SilentGhost

Answer 3

str.isspace() returns False for a valid and empty string

>>> tests = ['foo', ' ', 'rnt', '']
>>> print([s.isspace() for s in tests])
[False, True, True, False]

Therefore, checking with not will also evaluate None Type and '' or "" (empty string)

>>> tests = ['foo', ' ', 'rnt', '', None, ""]
>>> print ([not s or s.isspace() for s in tests])
[False, True, True, True, True, True]

Answered By: John Machin

Answer 4

You want to use the isspace() method

str.isspace()

Return true if there are only whitespace characters in the string and
there is at least one character, false otherwise.

That’s defined on every string object. Here it is an usage example for your specific use case:

if aStr and (not aStr.isspace()):
    print aStr

Answered By: Eric

Answer 5

Check the length of the list given by of split() method.

if len(your_string.split()==0:
     print("yes")

Or
Compare output of strip() method with null.

if your_string.strip() == '':
     print("yes")

Answered By: Bhavesh Munot

Answer 6

for those who expect a behaviour like the apache StringUtils.isBlank or Guava Strings.isNullOrEmpty :

if mystring and mystring.strip():
    print "not blank string"
else:
    print "blank string"

Answered By: kommradHomer

Answer 7

I’m assuming in your scenario, an empty string is a string that is truly empty or one that contains all white space.

if(str.strip()):
    print("string is not empty")
else:
    print("string is empty")

Note this does not check for None

Answered By: James Wierzba

Answer 8

Here is an answer that should work in all cases:

def is_empty(s):
    "Check whether a string is empty"
    return not s or not s.strip()

If the variable is None, it will stop at not sand not evaluate further (since not None == True). Apparently, the strip()method takes care of the usual cases of tab, newline, etc.

Answered By: fralau

Answer 9

I used following:

if str and not str.isspace():
  print('not null and not empty nor whitespace')
else:
  print('null or empty or whitespace')

Answered By: Emdadul Sawon

Answer 10

To check if a string is just a spaces or newline

Use this simple code

mystr = "      n  r  t   "
if not mystr.strip(): # The String Is Only Spaces!
    print("n[!] Invalid String !!!")
    exit(1)
mystr = mystr.strip()
print("n[*] Your String Is: "+mystr)

Answered By: Ahmed

Answer 11

Resemblence with c# string static method isNullOrWhiteSpace.

def isNullOrWhiteSpace(str):
  """Indicates whether the specified string is null or empty string.
     Returns: True if the str parameter is null, an empty string ("") or contains 
     whitespace. Returns false otherwise."""
  if (str is None) or (str == "") or (str.isspace()):
    return True
  return False

isNullOrWhiteSpace(None) -> True // None equals null in c#, java, php
isNullOrWhiteSpace("")   -> True
isNullOrWhiteSpace(" ")  -> True

Answered By: broadband

Check if string contains only whitespace

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