How can one negate a whole string in a regular expression in PHP?

To negate a whole string in a regular expression in PHP, you can use the negative lookahead assertion. This allows you to match a pattern only if it is not followed by another specific pattern. By using this technique, you can effectively negate a whole string in a regular expression. 

$string = "hello world";
$pattern = '/^(?!hello world$).*/';
if (preg_match($pattern, $string)) {
    echo "String does not match 'hello world'";
} else {
    echo "String matches 'hello world'";
}

Keywords

PHP regular expression negate string pattern

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