How also to use int() and format() functions in Python

The aim of this page📝 is to provide examples of usage of built-in functions int() and format() used in the primitive one-liner solution of https://leetcode.com/problems/add-binary/solution/. A more general lesson is that apart from learning algorithms, it is good to solve puzzles with the built-in functions and study them to learn the used language.

1. CODE

def ab(a,b):
  return format((int(a,2) + int(b,2)),"b")

2. int()

• usually used for the casting of string into integer
• but can be used for base conversion, too, with the second, optional base argument

class int(x, base=10)

• the allowed values for the base are 0 and 2–36.

BASE | PREFIX | MEANING
-----|--------|--------
2    | 0b/0B  | binary
8    | 0o/0O  | octal
16   | 0x/0X  | hex

• these correspond to integer literals in code

3. format()

• there is a Format Specification Mini-Language aka format specs in python
• format specs are used within replacement fields
• replacement fields are substrings of a format string

>>> bin(108)
'0b1101100'
 --*******
--*******: formt string
--: replacement fields

• format specs defined how replacement fields are presented
• the format function takes two arguments

format(value[, format_spec])

• In

format((int(a,2) + int(b,2)),"b")

…"b" specifies that the passed value is a binary

• format() converts the integer into a binary integer literal without 0b prefix
• I find this more elegant than using bin() with slicing

format(int("108"), "b")
>>> '1101100'
bin(108)[2:]
>>> '1101100'

4. LINKS

• format > Built-in Functions > Python 3.10.6 documentation
• format specs > Python 3.10.6 documentation
• int > Built-in Functions > Python 3.10.6 documentation
• https://leetcode.com/problems/add-binary/description/
• https://leetcode.com/problems/add-binary/solution/