Binary number converted into an integer

Question

I started learning Python recently. I have a problem understanding this:

print(int('0b101', 2))

I understand that it is a binary number that's going to be converted to an integer. But why the base should be 2? and can somebody explain what is the base? Thank you

• thibsc: The base is the number of digit you use to display your number. Binary is a base 2 because it uses 0 and 1, the decimal is base 10 because you use from 0 to 9
• MisterMiyagi: A binary number literally means a number expressed in base 2. This is the same as a decimal number is a number expressed in base 10. There is no other base that is appropriate.
• Fred Larson: Some good reading: en.wikipedia.org/wiki/…
• wjandrea: Sounds like you need to learn what binary is. BTW welcome to SO! Check out the tour and How to Ask if you want advice.

Answer 1

If no base is given, int defaults to base 10, rather than guessing what base the literal is. For example, 0b101 is also a valid hexadecimal literal:

>>> int('0b101', 16)
45313
>>> int('0xb101', 16)
45313

If you don't want it to be treated as base-10, you have to be explicit about how it should be treated.

>>> int('0b101', 2)
5

Answer 2

It says what number system your string is in currently. In a binary system, you have only two digits, i.e. 1 and 0. In decimal, you have 10, i.e. 0-9.

See few examples here on Programiz

I hope it clears something!