What is ! in php, if we add it before some function like

[AkhilKokani]

What is ! in php, if we add it before some function like !preg_match

Here’s the example :

$name = test_input($_POST["name"]);
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
  $nameErr = "Only letters and white space allowed"; 
}

[SamA74]

! means ‘not’.
So the condition is met if the rule returns false.

[Lemon_Juice]

@SamA74

So the condition is met if the rule returns false.

To be more precise - not necessarily false but a falsy value like false, null, 0, empty string or empty array. preg_match normally returns a number 0 or 1. false is returned when there is an error (the regex is incorrect).