08_boolean_functions.py

#======================================================================================
#                               BOOLEAN FUNCTIONS
#--------------------------------------------------------------------------------------
# Boolean: Can be either True or False
# used to handle logic and decision-making
# python uses bool to check conditions (yes/no, right/wrong).
#======================================================================================


#======================================================================================
# Boolean from values
#======================================================================================
print(True)
print(False)
print(type(True))

#======================================================================================
# Functions & Methods that return True or False as output
#--------------------------------------------------------------------------------------
# bool(value)   --built-in function     / output: bool
# True -- if the value is non-empty or non-zero
# False -- if the value is empty or zero
#======================================================================================
print(bool(123))        #True
print(bool("hello"))    #True
print(bool(1))          #True
print(bool(0))          #False
print(bool())           #False
print(bool(""))         #False
print(bool(None))       #False

#======================================================================================
# any() & all() are built-in functions used with lists, tuples, sets etc.
# They return True or False
#======================================================================================
email = "BOb@123"
phone = "23456"
username = "David Wilson"
print(any([email, phone, username]))

#--------------------------------------------------------------------------------------
# any()--True if at least one value is True
#--------------------------------------------------------------------------------------
# ex: allow registration if any field is filled
print(any([email, phone, username]))

#--------------------------------------------------------------------------------------
# all()--True only if all values are True
#--------------------------------------------------------------------------------------
# ex: allow registration only if all fields is filled
print(all([email, phone, username]))

#--------------------------------------------------------------------------------------
# isinstance(value, type)--checks if a value belongs to certain data 
# type.(built-in function / output:bool)
#--------------------------------------------------------------------------------------
print(isinstance(2, int))


#--------------------------------------------------------------------------------------
# startswith(substring)--checks if the string begins with a specific 
# word.(str method / output: bool)
#--------------------------------------------------------------------------------------
txt = "Hello"
print(txt.startswith("H"))

#--------------------------------------------------------------------------------------
# endswith(substring)--checks if the string ends with a specific
#  word.(str method / output: bool)
#--------------------------------------------------------------------------------------
print(txt.endswith("o"))

#--------------------------------------------------------------------------------------
# 'substring' in 'sting' -- checks if a word exists in the string.
#--------------------------------------------------------------------------------------
print("o" in txt)

#--------------------------------------------------------------------------------------
# isalpha()--checks if the string has only letters.
#--------------------------------------------------------------------------------------
country = "USA"
print(country.isalpha())

country = "USA1"
print(country.isalpha())
#--------------------------------------------------------------------------------------
# isnumeric()--checks if the string has only numbers.
#--------------------------------------------------------------------------------------
phone = "0987612345"
print(phone.isnumeric())
# . and - considered as special character that's why it is showing false in output
phone = "123-456-789"
print(phone.isnumeric())

price = "4.50"
print(price.isnumeric())