Python oct() Function

The oct() function in Python converts an integer number into its octal string representation, prefixed with 0o.

Octal numbers use base 8 and are often used in file permissions and low-level computing.

Syntax

oct(number)

Parameters:

• number – A valid integer (positive or negative)

Returns:

• A string that represents the octal value of the integer, prefixed with 0o

Example 1: Convert a Positive Integer to Octal

print(oct(10))

0o12

Explanation: 10 in decimal = 1×8 + 2 = 12 in octal

Example 2: Convert a Negative Integer

print(oct(-25))

-0o31

Explanation: The sign is preserved, and 25 in decimal = 3×8 + 1 = 31 in octal.

Example 3: Use with Hex or Binary Converted Values

print(oct(int('0xA', 16)))   # Hexadecimal to Octal

0o12

Explanation: 0xA (hex) = 10 (decimal) → 0o12 (octal)

Common Use Cases

• Understanding file permission bits in Unix/Linux systems (e.g., chmod 755)
• Working with low-level binary/octal representations
• Debugging bitwise operations or memory layouts

Important Notes

• oct() only accepts integers. Passing a float or string will raise a TypeError.
• The result is always a string, starting with 0o.

Interview Tip

Functions like bin(), oct(), and hex() are often used in bit manipulation problems. Know how to use them and convert between bases.

Summary

• oct(n) returns the octal string representation of an integer n.
• The result starts with 0o and is always a string.
• Useful in systems programming, permissions, and binary logic.

Practice Problem

Write a Python program that reads a number from the user and prints its binary, octal, and hexadecimal forms.

num = int(input("Enter a number: "))
print("Octal:", oct(num))
print("Binary:", bin(num))
print("Hexadecimal:", hex(num))