why I get error when using int() function to convert float to integer?

Question

Why do I get an error When I tried to use int() function to convert a float to integer?

>>> int('99.99')
Traceback (most recent call last):
  File "<pyshell#27>", line 1, in <module>
    int('99.99')
ValueError: invalid literal for int() with base 10: '99.99'

I expected the result to be 99

Answer 1

Your argument isn't a float, it's a string containing the representation of a float. You have to convert it to a float first, then you can convert that to an int.

int(float('99.99'))

Answer 2

Per the docs

Return an integer object constructed from a number or string x, or return 0 if no arguments are given. If x is a number, return x.int(). For floating point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in radix base.

Pay particular attention to "representing an integer literal". So your str that you are attempting to convert cannot be a float, because that's a float literal, not an int literal.

So, as others have noted, you cannot go directly from a float literal to an int, you need to convert the float first:

x = '123.45'

int(float(x))

Answer 3

You are getting a ValueError because you are overloading int() with an argument that is not consistent with the Python docs.

According to the doc:

"If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal "

Basically, x (in your case '99.99') is the string 99.99 which does not satisfy the requirements of being an integer literal. You provided a floating literal.

TL;DR

int(float('99.99'))