Regular Expressions Cookbook

6.3. Binary Numbers

Problem

You want to find binary numbers in a larger body of text, or check whether a string variable holds a binary number.

Solution

Find a binary number in a larger body of text:

\b[01]+\b

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Check whether a text string holds just a binary number:

\A[01]+\Z

Regex options: None

Regex flavors: .NET, Java, PCRE, Perl, Python, Ruby

^[01]+$

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python

Find a binary number with a B suffix:

\b[01]+B\b

Regex options: Case insensitive

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Find a binary byte value or 8-bit number:

\b[01]{8}\b

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Find a binary word value or 16-bit number:

\b[01]{16}\b

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Find a string of bytes (i.e., a multiple of eight bits):

\b(?:[01]{8})+\b

Regex options: None

Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Discussion

All these regexes use techniques explained in the previous two recipes. The key difference is that each digit is now a 0 or a 1. We easily match that with a character class that includes just those two characters: ‹[01]›.

See Also

Recipes 2.3 and 2.12