How to Convert an Octal String to an Integer in Python?

In Python, you can use the int() method (with a base 8 as the second argument) to convert an octal string to its integer equivalent, for example, like so:

num = int('30071', 8)

print(num) #=> 12345

This also works with octal strings that have the "0o" (or "0O") octal radix prefix:

# Python 2.6+
num = int('0o30071', 8)

print(num) #=> 12345

# Python 2.6+
num = int('0O30071', 8)

print(num) #=> 12345

Specifying an invalid octal number would raise the following error:

// ValueError: invalid literal for int() with base 8: '0x30071'
int('0x30071', 8)

If the octal string has 0o (or 0O) radix prefix, then you may also specify 0 as the second argument (i.e. the base) to the int() method, which would make it infer the value:

# Python 2.6+
num = int('0o30071', 0)

print(num) #=> 12345

This could be useful, for example, if a variable with a number can be of different types (such as binary, octal, hexadecimal, etc.).