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

Find a binary number in a larger body of text:

[01]+

Check whether a text string holds just a binary number:

A[01]+

^[01]+$

Find a binary number with a 0b prefix:

0b[01]+

Find a binary number with a B suffix:

[01]+B

Find a binary byte value or 8-bit number:

[01]{8}

Find a binary word value or 16-bit number:

[01]{16}

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

(?:[01]{8})+

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]›.

All the other recipes in this chapter show more ways of matching different kinds of numbers with a regular expression.

Techniques used in the regular expressions in this recipe are discussed in Chapter 2. Recipe 2.3 explains character classes. Recipe 2.6 explains word boundaries. Recipe 2.12 explains repetition.