Python oct() is a built-in function that returns the octal representation of an integer and the octal value is prefixed with '0o'.

Python oct() Syntax

oct(num)

Python oct() function takes only one parameter as an argument.

• num (required) – Integer value that is to be converted into an octal string

Note: If num is not a Python integer object, it has to define an __index__() method that returns an integer.

Python oct() Example

>>> #binary numbers
>>> oct(0b10101)
'0o25'  #corresponding octal string

>>> #decimal numbers
>>> oct(55)
'0o67'  #corresponding octal string

>>> #Hexadecimal numbers
>>> oct(0XAB)
'0o253'  #corresponding octal string

In above example, you can see the octal conversion of simple numerals.

Now, let’s see how we can use Python oct() function for custom objects.

Python oct() Example #2: Implementing __intex__() for custom objects

class Employee:
  salary = 45000

  def __index__(self):
     return self.salary

  #Use __int__() method for older version's compatibility
  def __int__(self):
     return self.salary

#Creating a new object of class Employee
emp_salary = Employee()
print('Salary in Octal is:', oct(emp_salary))

Output

Salary in Octal is: 0o127710

Here instead of passing integer value, we have supplied a custom object of class Employee to convert salary into octal value.

Now some of you may wonder if there is any way to use oct() function without the prefix 0o. Well yes, there is a way.

Using Python oct() without Oo

This is achieved by truncating the first two character of the output. This might remove the perfixing 0o but we do not recommend doing this in real time programs.

>>> oct(0XAB)[2:]
'253'

>>> hex(22)[2:]
'26'

Note that this method will break in negative values of the parameter.

Here is the example.

>>> oct(-25)
'-0o31'

>>> #Now using [2:]
>>> oct(-25)[2:]
'o31'

This is because we are truncating only first two characters, hence only - and 0 gets removed and o remains there.

So, for negative values 3 should be used instead of 2.

>>> oct(-25)[3:]
'31'