The bin() built-in function of Python

Function signature:

bin(integerNum)

Parameters:

integerNum - An integer in base-10, base-16, base-8 and base-2 format. In other words any integer following decimal(not to be made ambiguity with fractions), hexadecimal, octal or binary number systems.

Return value:

A binary string. A string containing 1s and 0s.

Overview:

The bin() function returns the binary representation of an integer as a string. The function takes an integer of base-10, base-16, base-8 and base-2 format as input and returns the binary string of bits - ones and zeros. A binary number follows base-2 format.
The binary string will have a prefix '0b' denoting binary value. Note that the returned binary string is a valid Python expression which can be passed inside the function eval() to get the integer value back in base-10 format.
For the bin() function to accept any object representing an integer value as parameter, the corresponding class should have the __index__() method defined.
If the binary string needs to be prefixed with zeros based on a given width, function like numpy.binary_repr() can be used.
A binary number has a base of 2. The maximum value of a digit in binary number system is 1. The minimum value is 0. A binary digit is often called a “bit”. A binary digit assumes one of the values: 0 or 1.

Exceptions:

The bin() function will raise a TypeError if an invalid type e.g., a floating point value is passed as a parameter.

Example 1 - Converting an integer to binary string:

# Example Python program that converts
# integers of base-10, base-16, base-8 and base-2
# into binary strings using the built-in function bin()

# Convert decimal number to binary string
num = 8
binString = bin(num)
print(binString)

# Convert hexadecimal number to binary string
num = 0xE0
binString = bin(num)
print(binString)

# Convert octal number to binary string
num = 0o370
binString = bin(num)
print(binString)

# Convert binary number to binary string
num = 0b1001
binString = bin(num)
print(binString)

Output:

0b1000

0b11100000

0b11111000

0b1001

Example 2 - Convert a custom integer object to binary string:

This Python example code below creates a custom integer class by defining class IntClass. The IntClass implements the __index__() method and returns the integer value it represents. When the built-in bin() function is called by passing an object of IntClass as parameter, the __index__() method is invoked internally by the bin() function and the returned integer value is converted to a string of binary bits - 1s and 0s.

# class representing a numeric val

class IntClass:

myVal = 0

def __init__(self, aVal_in):

self.myVal = aVal_in

#Has to define the __index__() method

def __index__(self):

return self.myVal

#Use bin() to convert an IntClass instance

CustomInt = IntClass(2)

CustomIntBinary = bin(CustomInt)

print("Custom integer object as binary string:{}".format(CustomIntBinary))

Output:

Custom integer object as binary string:0b10