Can someone explain the working of the statement in the provided piece of code?-CodePudding

I have just started OOPs in python and came across this piece of code . I was trying to understand the code in https://pythontutor.com/render.html#mode=display but could not understand the output of first if statement , if float value is passed(like the code). Secondly , during visualizing the code in the mentioned link , third statement is skipped , cannot understand why ? It will really be helpful if someone , can that I am unable to understand .

class CheckValue:
    @staticmethod
    def is_integer(num):
         if isinstance(num, float):
             return num.is_integer()
         elif isinstance(num, int):
             return True
         else:
             return False

val = CheckValue.is_integer(10.5)


print(val)

CodePudding user response：

10.5 is a float, so isinstance(num, float) will be true, and the first if block is executed.

The float.is_integer() method tells whether the float is equivalent to an integer, i.e. it has a .0 fraction. Since 10.5 doesn't have a zero fraction, num.is_integer() returns False, and that's returned by the function.

If you were to call CheckValue.is_integer(10), the first if condition would fail, because 10 is an int, not a float. The the next condition, isinstance(num, int), would be tested. This will be true, so return True will be executed.

Finally, if neither of these conditions is true, the else: block is executed and the function returns False. You can see this if you call it with a non-numeric argument, CheckValue.is_integer("123"). "123" is a string, so neither of the isinstance() calls will be true.

CodePudding user response：

def is_integer(num):
    # If num is of type `float` (i.e. a decimal number)...
    if isinstance(num, float):
       # use the member function of `float`s to determine whether
       # it's an integer or not, and return that value.
       return num.is_integer()
    # Else, if num is of type `int`...
    elif isinstance(num, int):
       # ...just return true because `int`s are always integers
       return True
    # In any other case (for example if you pass a
    # letter instead of a number)
    else:
       # return false, as only integers are integers.
       return False