Python bin() function

The Python function bin() returns the binary representation of a given integer. 
In case a non-integer class is given, the __index__() method is used.

bin() on integer


int1 = 5
print(bin(int1))


In this example, the binary representation of the integer is returned. The prefix 0b is included to indicate a binary representation.

0b101

remove prefix

To remove the prefix, we slice off the prefix:


int1 = 5
print(bin(int1)[2:])


to receive just the binary code:


101


reverse bin() function

To reverse the bin() function we simply use the int() function:


int1 = 5
bin1 = bin(int1)
print(int(bin1, 2))


to receive the original integer again:

5

bin() on non-integer


class Calc:
    a=2.5
    b=2.5
    def __index__(self):
        return int(self.a + self.b);

calc1 = Calc()
print(bin(calc1))


The binary representation of the sum 5 is returned:

0b101


bin() syntax

The syntax of the bin() function is:

bin(integer)

bin() arguments

The bin() function takes exactly one argument of type integer. 
If more or less than one argument is given, a TypeError exception is raised.
If a non-integer type is given, a TypeError exception is raised as well.

bin() return values

The bin() function returns the binary representation of a given integer. The return value is prefixed with 0b, and the type of the return value is str.