Detect if string is binary

Question

How can I determine if a string contains non-printable characters/is likely binary data?

This is for unit testing/debugging -- it doesn't need to be exact.

Answer 1

This will have to do.

function isBinary($str) {
    return preg_match('~[^\x20-\x7E\t\r\n]~', $str) > 0;
}

Answer 2

To search for non-printable characters, you can use ctype_print (http://php.net/manual/en/function.ctype-print.php).

Answer 3

After a few attempts using ctype_ and various workarounds like removing whitespace chars and checking for empty, I decided I was going in the wrong direction. The following approach uses mb_detect_encoding (with the strict flag!) and considers a string as "binary" if the encoding cannot be detected.

So far i haven't found a non-binary string which returns true, and the binary strings that return false only do so if the binary happens to be all printable characters.

/**
 * Determine whether the given value is a binary string by checking to see if it has detectable character encoding.
 *
 * @param string $value
 *
 * @return bool
 */
function isBinary($value): bool
{
    return false === mb_detect_encoding((string)$value, null, true);
}