Numbersflags: g

Binary Number Literal

Match binary number literals like `0b1010` or `0B11110000`.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("\\b0[bB][01]+\\b", "g");
const input = "Mask = 0b1010, halfbyte = 0B1111";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Python (re) code

pyPython

import re

pattern = re.compile(r"\b0[bB][01]+\b")
input_text = "Mask = 0b1010, halfbyte = 0B1111"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`\b0[bB][01]+\b`)
	input := `Mask = 0b1010, halfbyte = 0B1111`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

\b0[bB][01]+\b   (flags: g)

Raw source: \b0[bB][01]+\b

How it works

\b is a word boundary so we don't match inside identifiers. 0[bB] matches the literal prefix (case-insensitive on the b). [01]+ matches one or more binary digits. Trailing \b prevents matching into adjacent word characters.