Overview
Introduction
This tool reads a list of sign-magnitude octal strings and converts each back into an ordinary base-10 integer.
It's the reverse of the Integer to Octal Converter: a leading "-" is treated as a sign, and the remaining digits are parsed as base-8.
What Is Octal to Integer Converter?
A converter that takes octal strings, one per line, and outputs the base-10 integer each one represents.
It's commonly useful for decoding Unix-style file permission numbers (like 644 or 755) back into their decimal values.
How Octal to Integer Converter Works
Each line is checked against a pattern allowing only an optional leading "-" followed by digits 0 through 7.
The digits after any sign are parsed as a base-8 number using JavaScript's `parseInt` with radix 8.
If the line started with "-", the parsed magnitude is negated.
When To Use Octal to Integer Converter
Use it to decode octal strings, including Unix permission notation, back into decimal.
It's also handy for checking octal homework or puzzles.
Often used alongside Integer to Octal Converter, Binary to Integer Converter and Integer Base Changer.
Features
Advantages
- Simple, readable sign-magnitude format without a fixed bit-width requirement.
- Clear validation that flags exactly which line has an invalid digit.
Limitations
- Requires digits to be strictly 0-7; other characters invalidate the line.
- Doesn't decode a fixed-width two's-complement bit pattern; only a plain leading "-" sign is recognized.
Examples
Best Practices & Notes
Best Practices
- When decoding Unix permission bits, remember the result is a plain decimal number, not a formatted permission string.
Developer Notes
Validates each line with `/^-?[0-7]+$/` before calling `parseInt(digits, 8)`, so malformed input fails with a specific per-line error rather than silently producing `NaN`.
Octal to Integer Converter Use Cases
- Converting Unix file permission numbers (like 755) to decimal
- Decoding octal output from the Integer to Octal Converter
- Checking octal arithmetic homework or puzzles
Common Mistakes
- Including digits 8 or 9, which aren't valid in octal and will be rejected.
- Expecting a fixed-width two's-complement interpretation instead of a plain sign-magnitude one.
Tips
- Use the companion Integer to Octal Converter to generate valid test input for this tool.