What is the bool() method in Python?
The bool() method returns either True or False, based on the specified object. If no object is passed, it returns False by default.
Syntax
The bool() method is declared as follows:
Parameter
Only one parameter can go inside the bool() method, be it a set, integer, string, list, dictionary, or character.
If no parameter goes inside the bool() method, it returns a False value.
Return value
True
The bool() method returns True if one of the following parameters is passed in it:
- a negative or positive integer.
- a non-empty string, list, dictionary, or set.
- a
Truevalue.
False
The bool() method returns False in the following cases:
- 0 (zero)
- an empty string, list, dictionary, or set.
- a
Falsevalue. - no parameter is passed.
Code
Example 1
In the example below, the bool() method will return False.
# Default case: no parameter passed to bool() methodprint "Default case:",bool()# Integer 0 goes inside bool() methodx = 0print "Integer 0:",bool(x)# Empty string goes inside bool() methody = ""print "Empty string:",bool(y)# Empty set goes inside bool() methodi = set()print "Empty set:",bool(i)# Empty list goes inside bool() methodj = []print "Empty list:",bool(j)# Empty dictionary goes inside bool() methodk = {}print "Empty dictionary:",bool(k)
Example 2
The example below shows the instances where the bool() method returns True.
# A true value goes inside bool() methodcheck = Trueprint "The check is",bool(check)# Positive integer goes inside bool() methoda = 1print "Positive integer:",bool(a)# Negative integer goes inside bool() methodb = -6print "Negative Integer:",bool(b)# Non-empty string goes inside bool() methodc = "Hello"print "Non-empty string:",bool(c)# Non-empty list goes inside bool() methodg = [1,2,3]print "Non-empty list:",bool(g)# Non-empty set goes inside bool() methodh = {1, 2, 3, 4}print "Non-empty set:",bool(h)# Non-empty dictionary goes inside bool() methodi = {"Language": "Python"}print "Non-empty dictionary:",bool(i)