question on function

vang

hi,
i've this line of code in my login php file. Everything is working fine.

if(!preg_match("/^[a-zA-Z0-9]{1,9}$/", $key))
...
other

To reuse the code, I remove this line from the login file, create a function and save in a separate php file name validate.php.

function validatekey($key)
{     if(!preg_match("/^[a-zA-Z0-9]{1,9}$/", $key))
       {     exit();
       }
}

By putting it this way, the logic seems to work in the reverse way!
I test the script, call the function, and input the correct key, the program exit! This is not correct.
i solve the problem by removing the ! sign in the line.

if(preg_match("/^[a-zA-Z0-9]{1,9}$/", $key))

But i do not understand why this is happening in this way? Or am i understand the wrong direction?
Any help is appreciated, thanks.

laserlight

Perhaps you used the function incorrectly. This:

if (!preg_match('/^[a-zA-Z0-9]{1,9}$/', $key))
{
    // invalid key
}
else
{
    // valid key
}

is equivalent to:

function isValidKey($key)
{
    return preg_match('/^[a-zA-Z0-9]{1,9}$/', $key) == 1;
}

if (!isValidKey($key))
{
    // invalid key
}
else
{
    // valid key
}

vang

How about this statement that i've seen on internet:

if(mail($from, $to, $subject, $message))
{     echo 'mail send';
}
else
{    echo 'mail not send';
}

The above sounds logic to me, but when i try it out myself, again it works on the reverse way!

i 've to re-correct it and then it become

if(mail($from, $to, $subject, $message))
{    echo 'mail not send';
}
else
{     echo 'mail send';
}

Then the whole thing work logically. So wierd! Is there any explanation or am i missing something?

NogDog

Not sure if this is the issue here, but note that mail() only returns false if it is immediately rejected by the sendmail program (or whatever it is using to send it). If the mailing fails at any point further downstream in the whole email transmission/acceptance process, the PHP mail function will not know about it and will have already returned true to your program.