Python Bin() Function

Function Name:


Function Overview:

  • The bin() function returns the binary representation of an int object as a string.It takes an integer in decimal format and converts it to binary format.
  • The returned value is of type string containing the binary value of the integer.
  • The binary string will have a prefix '0b' denoting binary value. Remember that the returned binary string is a valid python expression which can be passed inside the function eval() to get the integer value back.
  • For the bin() function to work on any other object representing an integer value the class corresponding that object has to defined with a __index__() method.



# Define an integer value

x = 10


# convert the integer to a binary string

binaryString = bin(x)


print("Binary string of {} is {}".format(x, binaryString))


#convert the binary back to decimal

y = eval(binaryString)


print("Binary converted back to decimal:{}".format(y))



Binary string of 10 is 0b1010

Binary converted back to decimal:10



# 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))



Custom integer object as binary string:0b10



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

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