How to check if a variable is empty in python

Question

I am wondering if python has any function such as php empty function  http   php net manual en function empty php  which check if the variable is empty with following criteria      an empty string  0  0 as an integer  0 0  0 as a float   0   0 as a string  NULL FALSE array    an empty array

User · Answer

See section 5 1   http   docs python org library stdtypes html  Any object can be tested for truth value  for use in an if or while condition or as operand of the Boolean operations below  The following values are considered false   None  False  zero of any numeric type  for example  0  0L  0 0  0j   any empty sequence  for example               any empty mapping  for example       instances of user-defined classes  if the class defines a   nonzero     or   len     method  when that method returns the integer zero or bool value False   1   All other values are considered true     so objects of many types are always true   Operations and built-in functions that have a Boolean result always return 0 or False for false and 1 or True for true  unless otherwise stated   Important exception  the Boolean operations or and and always return one of their operands

User · Answer

Just use not   if not your variable      print  your variable is empty     and for your 0 as string use   if your variable     0       print  your variable is 0  string      combine them   if not your variable or your variable     0       print  your variable is empty     Python is about simplicity  so is this answer

User · Answer

See also this previous answer which recommends the not keyword  How to check if a list is empty in Python   It generalizes to more than just lists    gt  gt  gt  a       gt  gt  gt  not a True   gt  gt  gt  a       gt  gt  gt  not a True   gt  gt  gt  a   0  gt  gt  gt  not a True   gt  gt  gt  a   0 0  gt  gt  gt  not a True   gt  gt  gt  a   numpy array      gt  gt  gt  not a True   Notably  it will not work for  0  as a string because the string does in fact contain something - a character containing  0   For that you have to convert it to an int    gt  gt  gt  a    0   gt  gt  gt  not a False   gt  gt  gt  a    0   gt  gt  gt  not int a  True

User · Answer

Yes  bool  It s not exactly the same --  0  is True  but None  False      0  0 0  and    are all False    bool is used implicitly when you evaluate an object in a condition like an if or while statement  conditional expression  or with a boolean operator   If you wanted to handle strings containing numbers as PHP does  you could do something like   def empty value       try          value   float value      except ValueError          pass     return bool value

[python] How to check if a variable is empty in python?

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