What counts as valid unary input?

Each line must contain only "1" characters, optionally preceded by a single "-" for a negative value. Any other digit or character makes that line invalid.

What does a blank line convert to?

A blank line has zero "1" characters, so it converts to 0, matching how the Integer to Unary Converter represents zero.

Why is this different from other list tools that skip blank lines?

Most list tools in this category skip empty lines as formatting whitespace. Here, an empty line is itself meaningful unary data (zero repetitions), so it's read as 0 instead of being skipped.

What happens with a line like "12"?

It's rejected, since "2" isn't a valid unary character; only "1"s (and an optional leading "-") are allowed.

Unary to Integer Converter - Convert Tally Marks to Numbers

Overview

Introduction

This tool reverses unary notation back into ordinary base-10 integers: it counts how many "1" characters appear on each line and reports that count, honoring a leading "-" as a sign.

It pairs with the Integer to Unary Converter to let you round-trip values between the two representations.

What Is Unary to Integer Converter?

A converter that reads a list of unary strings, one per line, and outputs the integer each one represents by counting its "1" characters.

Unlike most list-based tools here, a blank line isn't skipped as filler whitespace; it's read as the unary representation of zero.

How Unary to Integer Converter Works

Each line is checked against a pattern allowing only an optional leading "-" followed by zero or more "1" characters.

The tool counts the "1"s on the line to get the magnitude, then applies a negative sign if the line started with "-" and the count is greater than zero.

Any line containing a character other than "1" or a single leading "-" is rejected with an error naming that line.

When To Use Unary to Integer Converter

Use it to check or grade unary strings produced by hand, by a textbook exercise, or by another tool.

It's useful alongside the Integer to Unary Converter when teaching or demonstrating base-1 notation.

Often used alongside Integer to Unary Converter and Binary to Integer Converter.

Features

Advantages

Simple, predictable counting logic that's easy to verify by hand for small inputs.
Explicitly validates input, rejecting anything that isn't pure unary rather than guessing.

Limitations

Only recognizes "1" as the unary symbol; other tally conventions (like groups of five) aren't supported.
Long unary strings are tedious to read and error-prone to type by hand, which is inherent to the notation itself, not a limitation of this tool.

Examples

Positive unary string

Input

Output

Negative unary string

Input

-111

Output

-3

Best Practices & Notes

Best Practices

Double-check pasted unary strings for stray characters (spaces, other digits) before conversion, since any non-"1" character invalidates the line.

Developer Notes

Each line is tested against `/^-?1*$/` rather than trimmed and counted blindly, so any stray character fails fast with a specific error; the count of matched "1"s becomes the magnitude, and the leading "-" (if present and the count is nonzero) applies the sign.

Unary to Integer Converter Use Cases

Verifying unary output produced by the companion Integer to Unary Converter
Grading or checking unary notation exercises
Decoding tally-style strings back into ordinary numbers

Common Mistakes

Pasting in a decimal number instead of a unary string, which fails validation since digits other than "1" aren't allowed.
Expecting a blank line to be skipped like in other list tools, when here it deliberately means 0.

Tips

Use short test values first (like "111" or "-11") to confirm you understand the counting behavior before converting longer strings.

Unary to Integer Converter