What is the regex for hex string?

The regex pattern for hex string is `^[0-9a-fA-F]+$`. This pattern validates any-length hexadecimal string.

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^[0-9a-fA-F]+$/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'^[0-9a-fA-F]+$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^[0-9a-fA-F]+$/i`) or use `re.IGNORECASE` in Python.

Regex for Hex String

Regex Pattern

^[0-9a-fA-F]+$

Any-length hexadecimal string

Quick Answer

The regex pattern for hex string is `^[0-9a-fA-F]+$`. Any-length hexadecimal string. This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
deadbeef	✓ Matches
0x1234	✓ Matches
FF00FF00	✓ Matches
1a2b3c	✓ Matches
ghij	✗ No match
0xGG	✗ No match
not hex	✗ No match

Code Examples

javascript

const regex = /^[0-9a-fA-F]+$/;
const isValid = regex.test(value);

python

import re
pattern = r'^[0-9a-fA-F]+$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^[0-9a-fA-F]+$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^[0-9a-fA-F]+$/', $value)) {
    echo "valid";
}

java

String pattern = "^[0-9a-fA-F]+$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

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