Octal to Decimal Conversion in Python

Octal to Decimal Conversion

Octal to Decimal conversion is the process of converting an octal number (base-8) into its equivalent decimal number (base-10). Each octal digit represents a power of 8.

For example, the octal number 17 is equal to decimal 15 because:

(1 × 8¹) + (7 × 8⁰) = 8 + 7 = 15

We will explore three methods to convert an octal number to a decimal number using Python programming.

Method 1: Using Loop

We extract each digit of the octal number, multiply it by the corresponding power of 8, and sum the results.

def octal_to_decimal(octal):
    decimal, i = 0, 0
    while octal:
        last_digit = octal % 10
        decimal += last_digit * (8 ** i)
        octal //= 10
        i += 1
    return decimal

# Get user input
octal = int(input("Enter an octal number: "))
print("Decimal equivalent:", octal_to_decimal(octal))
            

Output:

Enter an octal number: 17
Decimal equivalent: 15

Method 2: Using Built-in Function

We can use Python's int() function to directly convert an octal number to a decimal number.

# Get user input
octal = input("Enter an octal number: ")
# Convert using built-in function
decimal = int(octal, 8)
print("Decimal equivalent:", decimal)
            

Output:

Enter an octal number: 17
Decimal equivalent: 15

Method 3: Using Recursion

We recursively extract each digit and multiply it by the corresponding power of 8.

def octal_to_decimal_recursive(octal, power=0):
    if octal == 0:
        return 0
    return (octal % 10) * (8 ** power) + octal_to_decimal_recursive(octal // 10, power + 1)

# Get user input
octal = int(input("Enter an octal number: "))
print("Decimal equivalent:", octal_to_decimal_recursive(octal))
            

Output:

Enter an octal number: 17
Decimal equivalent: 15