XML Extensible Markup Language

SIGNATURE = bytes.fromhex("3c3f786d6c")
OFFSET = 0

def is_xml(path: str) -> bool:
    with open(path, "rb") as f:
        f.seek(OFFSET)
        head = f.read(len(SIGNATURE))
    return head == SIGNATURE

const SIGNATURE = [0x3c, 0x3f, 0x78, 0x6d, 0x6c];
const OFFSET = 0;

// bytes: a Uint8Array / Buffer holding the start of the file
export function isXml(bytes) {
  return SIGNATURE.every((byte, i) => bytes[OFFSET + i] === byte);
}

package fileid

import "bytes"

var isxmlSignature = []byte{0x3c, 0x3f, 0x78, 0x6d, 0x6c}

const isxmlOffset = 0

func IsXml(b []byte) bool {
	end := isxmlOffset + len(isxmlSignature)
	if len(b) < end {
		return false
	}
	return bytes.Equal(b[isxmlOffset:end], isxmlSignature)
}

const SIGNATURE: &[u8] = &[0x3c, 0x3f, 0x78, 0x6d, 0x6c];
const OFFSET: usize = 0;

fn is_xml(bytes: &[u8]) -> bool {
    bytes.get(OFFSET..OFFSET + SIGNATURE.len()) == Some(SIGNATURE)
}

<?php
$signature = "\x3c\x3f\x78\x6d\x6c";
$offset = 0;

function is_xml(string $bytes): bool {
    global $signature, $offset;
    return substr($bytes, $offset, strlen($signature)) === $signature;
}