Type casting

Orc · 05-24-2008, 10:39 PM

When you make a variable look like a different data type, how is this done in php?

I mean if I try this:

PHP Code:


			
<?php

$string = "Hello World";
$string  = (int) $string;

// This to me sounds like the concept of type casting in php
// Now this only gives me 0 cause theres EDIT: NO -_- integers
// How do I change it back to a string, an integer to a string
// Maybe I don't understand the concept

?>

Village Idiot · 05-24-2008, 10:45 PM

When typecasting, you loose all non-int data. You can not change it back to "Hello World".

Orc · 05-25-2008, 12:06 AM

Quote:

Originally Posted by Village Idiot

When typecasting, you loose all non-int data. You can not change it back to "Hello World".

Alright, I'll just keep using zlib compression, using gzdeflate and inflate.

Village Idiot · 05-25-2008, 04:18 AM

What are you trying to do?

xenon · 05-25-2008, 11:55 AM

Type casting is not made so you can 'transform' strings into integers, arrays, objects, and so on. It's made so you can ENFORCE a certain data type. Its only use is that you can make sure you're getting a certain data type, so you can perform a certain operation. See the example:

PHP Code:


			
function sum_ints($a, $b)

{

    $a = (int) $a;

    $b = (int) $b;



    return $a+$b;

}

It's obvious that the sum function can't be used on strings, so that's why we use type casting, so we can enforce the parameters to be integers. If non-integer values are passed in, the function will simply return 0 instead of crashing if you pass in objects as parameters, therefore not breaking application flow. Operator overloading would come useful in here, but that's another problem.

Orc · 05-25-2008, 04:00 PM

Quote:

Originally Posted by xenon

Type casting is not made so you can 'transform' strings into integers, arrays, objects, and so on. It's made so you can ENFORCE a certain data type. Its only use is that you can make sure you're getting a certain data type, so you can perform a certain operation. See the example:

PHP Code:


			
function sum_ints($a, $b)

{

    $a = (int) $a;

    $b = (int) $b;



    return $a+$b;

}

It's obvious that the sum function can't be used on strings, so that's why we use type casting, so we can enforce the parameters to be integers. If non-integer values are passed in, the function will simply return 0 instead of crashing if you pass in objects as parameters, therefore not breaking application flow. Operator overloading would come useful in here, but that's another problem.

Thanks, also Village_Idiot, my main priority in making dynamic SQL Applications, is security, then features, and I like to encrypt the strings that go into the table, and the such and such, like always, you can give me tips on MySQL, though I've learned pretty much all of it, EXCEPT all the of proper security really, besides using comments and quotes to block certain things out so someone could do an sql injection.

I'm usually the paranoid type, when it comes to working on security, I'm always scared that someone would destroy my application, :( that is why I backup logs every time there are new active queries. I am going to extreme measures to make my own language or add a new extension in php, using C/C++.

ReSpawN · 05-25-2008, 06:08 PM

If you are interested in changing the type of variable, you can check out C# (CSharp) documentations on Microsoft. Among the common there is string, bool, int, double and char.

Orc · 05-25-2008, 06:20 PM

Quote:

Originally Posted by ReSpawN

If you are interested in changing the type of variable, you can check out C# (CSharp) documentations on Microsoft. Among the common there is string, bool, int, double and char.

Huh? This is php. :P

ReSpawN · 05-25-2008, 09:23 PM

Doesn't mean that PHP doesn't use functions originally designed for C++ and C#..?

Orc · 05-25-2008, 10:29 PM

Does typecasting specifically only make it where it changes to the data type and nothing more? Like the example I gave? :/ Like I want to change the data type back, I cannot now.

Orc · 05-25-2008, 10:30 PM

Posts: 666 - xD

delayedinsanity · 05-26-2008, 03:10 AM

Quote:

Originally Posted by Orc

Does typecasting specifically only make it where it changes to the data type and nothing more? Like the example I gave? :/ Like I want to change the data type back, I cannot now.

Type casting

Village Idiot · 05-26-2008, 03:53 PM

You can look at it like this.

If a variable was a room where a party was going on, the equal is the door, and the (int) typecast would be the guard at the door. ($room = (guard) $partygoer) He does not change the type of room it is or the people inside it, all he does is only let people with money go in. Same thing goes with that command, $var = (int) value; does not modify the variable, it filters what goes in.