Binary safe

A binary safe function means the function will work correctly when you pass it arbitrary binary data. i.e.

Strings containing non-ASCII bytes. (i.e. bangla font)
Null bytes. (i.e. null-terminated)

For instance, if PHP's strlen function worked like C standard library strlen, the result here would be wrong:

$str = "abc\x00abc";
echo strlen($str); //gives 7, not 3!

More examples:

<?php

    $string1 = "Hello";
    $string2 = "Hello\x00World";

    // This function is NOT ! binary safe
    echo strcoll($string1, $string2); // gives 0, strings are equal.

    // This function is binary safe
    echo strcmp($string1, $string2); // gives <0, $string1 is less than $string2.

?>

\x indicates hexadecimal notation. See: PHP strings

0x00 = NULL
0x04 = EOT (End of transmission)

ASCII table to see ASCII char list.

Labels: PHP, Web development

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