PHP force a var to have a certain type

This may be a stupid question but I might aswell as it :)

is there away to force

$tel1 = '05';// string
settype($tel1,'string');
$tel1 = 06;//either throw error, or convert it to string automatically.
var_dump($tel1);//(string [2]) 05

The above code is of the top of my head so might not be accurate but I need to keep a variable as a string not numeric, because of some silly thing I have done, now my phone numbers lose the leading 0s :-(

n I cn't rewrite it because it will mess up with other numeric types,b4 u ask it was an automated service for db to check if it was a numeric value or not,

UPDATE This is the problem

function escape($str){
   if(is_numeric($str)){
       return $str;
   }else{
       return "'".mysql_real_escape_string($str).'\'';
   }
}
$tel1 = "06";
$sql = 'SELECT * FROM blabla WHERE id = '.escape($tel1).'';
//above is same as below
$sql = 'SELECT * FROM blabla WHERE id = 06 ';

I can't change anything inside the scape function because other inputes thru开发者_如何学运维out the website are using this function, I dont wanna mess their validations.

Your use of is_numeric tests for numeric content, not an integer type. But then you take a variable called $str which implies you want it to be a string.

Perhaps use:

function escape($val) {
   if (is_numeric($val) && !is_string($val)) {
       return $val;
   }
   else{
       return "'" . mysql_real_escape_string($val) . '\'';
   }
}

Now strings will be escaped and quoted, but not if they contain only numeric content.

you can do something like:

$string = (string) $int;

or use a function

$string = strval($int);

You can't force a variable to a specific type in the global scope.

You can force Arrays and Objects in a function.

function getElementsByClassName(DOMNode $parentElement, Array $classNames) {
 ... 
}

If you pass an object that is not an instantiation of DOMNode (or a subclass), or if you don't pass an Array as the second argument, you'll get an error.

You can of course cast any variable, e.g. (string) $tel1.

You shouldn't be treating phone numbers as Ints anyway, because of leading zeroes and possible parenthesis and dashes. Also, once your telephone number is an Int, it won't know its 0 padding anymore because it will be discarded, so casting it back won't give you the original String.

To cast a variable you can use something like:

$i = 1;
$s = (string) $i;

Depending on the db adaptor you might not be able to detect the type being returned from the database. I believe it's PDO that returns everything (even INT values) as strings.

The number_format() function may be of use to you too.

If you declare a variable as:

$var = 06;

it immediately becomes 6 without leading zero because leading zero when it comes to integers is meaningless and therefore it's cut out.

In other words, your variable has to be created as string, which is what you probably deduced yourself.

Quick fix would be the following: you can add another parameter to your escape() function.

For example:

function escape($str, $force_str = false)
{
    if($force_str) 
    { 
        // do your conversion, the rest of the site will by default pass false so nothing will be broken 
    }
}

As alex said, start by making sure the phone number is never converted from string to int in your own code. Then, you need to make sure it will not be converted when sent to your SQL DB. It ought to work if you do it this way:

$sql = "SELECT * FROM blabla WHERE id = '" . mysql_real_escape_string($tel1) . "'";

This is the same as

$sql = "SELECT * FROM blabla WHERE id = '06'";