Procedural programming languages – stoimen's web log

PHP Strings Don’t Need Quotes

Stoimen — Thu, 26 Apr 2012 13:52:53 +0000

I bet you didn’t know that PHP strings don’t need quotes! Indeed PHP developers work with strings with either single or double quotes, but actually in some cases you don’t need them.

PHP by Book

Here’s how PHP developer declare a string, which is something very common in any programming language.

$my_var = 'hello world';
// or
$my_var = "hello world";

PHP Tricks

What if you do the following:

echo hello;

That appears to be correct … Well, it’s not absolutely correct. You’ll be “noticed”.

// Notice: Use of undefined constant hello
echo hello;

However if you disable error reporting, the code will be completely fine.

error_reporting(0);

// no problem now
echo hello;

Variations

What follows from the thing above is that you can use strings without quotes:

// hello
echo hello;

// hello world (concatenated)
echo hello . ' world';

// helloworld
echo hello . world;

However you can’t have spaces and most of the “special” symbols.

// syntax error
echo hello world;

// syntax error
echo hello!;

Final Words

Although you can do this in PHP, that is completely wrong. The code becomes more difficult to read and understand. In the second place you can miss a $ sign in front of a variable declaration and thus the PHP interpreter will assume this is a string. So disable error reporting isn’t so great sometimes.

Object Cloning and Passing by Reference in PHP

Stoimen — Thu, 27 Oct 2011 14:25:17 +0000

In PHP everything’s a reference! I’ve heard it so many times in my practice. No, these words are too strong! Let’s see some examples.

Some developers think that everything's passed by reference in PHP.

Passing Parameters by Reference

Clearly when we pass parameters to a function it’s not by reference. How to check this? Well, like this.

function f($param)
{
	$param++;
}

$a = 5;
f($a);

echo $a;

Now the value of $a equals 5. If it were passed by reference, it would be 6. With a little change of the code we can get it.

function f(&$param)
{
	$param++;
}

$a = 5;
f($a);

echo $a;

Now the variable’s value is 6.

So far, so good. Now what about copying objects?

Objects: A Copy or a Cloning?

We can check whether by assigning an object to a variable a reference or a copy of the object is passed.

class C
{
	public $myvar = 10;
}

$a = new C();
$b = $a;

$b->myvar = 20;

// 20, not 10
echo $a->myvar;

The last line outputs 20! This makes it clear. By assigning an object to a variable PHP pass its reference. To make a copy there’s another approach. We need to change $b = $a, to $b = clone $a;

class C
{
	public $myvar = 10;
}

$a = new C();
$b = clone $a;

$b->myvar = 20;

// 10
echo $a->myvar;

Arrays by Reference

What about arrays? What if I assign an array to a variable?

$a = array(20);

$b = $a;
$b[0] = 30;

var_dump($a);

What do you think is the value of $a[0]? Well, the answer is: 20! So $b is a copy of the array “a”. Instead you should assign explicitly its reference to make “b” point to “a”.

$a = array(20);

$b = &$a;
$b[0] = 30;

var_dump($a);

Now $a[0] equals 30!

I think this could be useful!

Does JavaScript undefined Equals undefined?

Stoimen — Fri, 21 Oct 2011 11:36:01 +0000

Weird JS

Does JavaScript "undefined" equals "undefined"?

As you know sometimes JavaScript can be weird. Let’s see the following example and let’s try to answer the question: does “undefined” equals “undefined”. What do I mean?

First take a look at the following code.

var a;
var b = undefined;

// alerts "false"
alert(b == a);

Both a and b are undefined, but they are NOT equal. Now let’s see where it can become a problem.

We have an object with one member variable that is not defined.

var f1 = function()
{
	this.myvar;
};

var obj1 = new f1();

Now you’d like to know whether the object “b” has the property “myvar”. There are lots of examples online, but what’s the right way?

Wrong

Appearantly the value of b.myvar should be undefined.

alert(obj1.myvar); // undefined

But that doesn’t mean that it is the same value if the object was declared this way:

var f2 = function()
{
	this.myvar = undefined;
};

var obj2 = new f2();

This is a completely different thing. Why? In the first case if we try to check whether the property myvar belongs to obj1 we can go wrong with:

if (obj1.myvar) // false

This is false simply because obj1.myvar is undefined

if (obj2.myvar) // false

Again is false, because obj2.myvar is undefined.

The same thing happen when using the other “famous” approach.

if (typeof obj1['myvar'] != 'undefined') // false
if (typeof obj2['myvar'] != 'undefined') // false

Clearly this is not the right answer, becase even it is undefined myvar belongs to obj2!

Right

Now let’s try with hasOwnProperty supported by almost every modern browser.

if (obj1.hasOwnProperty('myvar')); // false
if (obj2.hasOwnProperty('myvar')); // true

Here you can see that when the member variable is explicitly defined as “undefined” the object “has the property” and hasOwnProperty returns true. Yet again, “undefined” does not always equal to “undefined”.

HTTP POST with PHP without cURL

Stoimen — Tue, 07 Sep 2010 21:47:27 +0000

Awesome PHP

It’s strange how powerful PHP can be. There’s a legend that cURL is the only way to perform a HTTP POST with PHP, but that isn’t the truth. An extremely useful script is by using stream_context_create:

$optional_headers = null;
$params = array('http' => array(
                'method' => 'POST',
                'content' => http_build_query(array('name' => 'my-name'))));

if ($optional_headers !== null) {
    $params['http']['header'] = $optional_headers;
}

$ctx = stream_context_create($params);
$fp = @fopen('http://example.com/post.php', 'rb', false, $ctx);

Well this is only a snippet. You can change a lot this code and perform any request, but here’s a small start up. However note that this will do the same as while posting to example.com/post.php via web form!

Friday Algorithms: Quicksort – Difference Between PHP and JavaScript

Stoimen — Fri, 11 Jun 2010 07:13:01 +0000

Here’s some Friday fun. Let me show you one sorting algorithm, perhaps the most known of all them – the quick sort, implemented both on PHP and JavaScript. Although the code look similar between both languages, there are few differences, that show the importance of the syntax knowledge!

1. PHP


2. JavaScript
var a = [2,4,5,63,4,5,63,2,4,43];

function quicksort(arr)
{
    if (arr.length == 0)
        return [];

    var left = new Array();
    var right = new Array();
    var pivot = arr[0];

    for (var i = 1; i < arr.length; i++) {
        if (arr[i] < pivot) {
           left.push(arr[i]);
        } else {
           right.push(arr[i]);
        }
    }

    return quicksort(left).concat(pivot, quicksort(right));
}

console.log(quicksort(a));

Note that the first conditional statement is quite important! While in PHP the count function will return 0 either on a NULL value or an empty array and you can substitute it with something like count($array) < 2
if (count($array) < 2)
	return $array;

in JavaScript you cannot use that because of the presence of the 'undefined' value when an "empty" array is passed as an argument. Thus you've the conditional above:
// this will result with an error
if (arr.length < 2)
        return arr;

Coming Up Next ...
An iterative version of the algorithm next Friday!

Related posts:

Friday Algorithms: Sorting a Set of Integers – Far Quicker than Quicksort! 
Friday Algorithms: Iterative Quicksort 
JavaScript Objects Coding Style 
Friday Algorithms: JavaScript Bubble Sort

JSON and Zend Framework? – Zend_Json

Stoimen — Thu, 10 Jun 2010 14:08:59 +0000

That’s really a good Zend Framework’s class that help you do the encode/decode job very easily. First of all it escapes everything for you and second it prints a correct/valid code. Note that sometimes if you have a trailing whitespace after the closing PHP tag – ?> that will result in an error.

Here’s some code:

public function jsonAction()
{
	$data = array(3,4,'test', 'my-name' => 3,4);

	echo Zend_Json::encode($data);

	$this->_helper->viewRenderer->setNoRender(true);
	$this->view->layout()->disableLayout();
}

and the result is:

{"0":3,"1":4,"2":"test","my-name":3,"3":4}

Note that all integers are printed without double quotes – which saves some space!

JavaScript Objects Coding Style

Stoimen — Mon, 24 May 2010 07:48:50 +0000

JavaScript vs. PHP

Continuing from my post about PHP arrays coding style and following the comments of that post, I’d like to write a bit about JavaScript objects’ coding style.

You perhaps know that the term object is quite undefined or under estimated in the JavaScript world, but I’d speak about the key/value pairs in JS commonly formatted like that:

var obj = { key : 'value' }

Here you can add more and more key/value pairs, but what’s different from the PHP associative arrays and what’s the same and should be cosidered.

The Same as PHP?

I wrote about the alignment in PHP and hashes. Than I showed how I align them:

$arr = array(
   'short'   => 'val',
   'longkey' => 'val'
);

In JavaScript you should use the same technique of alignment:

var obj = {
   'short'   : 'val',
   'longkey' : 'val'
};

Some Differences

Yes, there are more differences, which is normal. First of all you don’t have the => notation in JavaScript and a : is used. Second and most important you cannot add a trailing comma after the last key/value pair. Note that in PHP that’s fine!

// that will throw an error in MSIE
var obj = {
   'short'   : 'val',
   'longkey' : 'val',
};

while this is OK in PHP and it’s encouraged:

$arr = array(
   'short'   => 'val',
   'longkey' => 'val',
);

PHP Associative Arrays Coding Style

Stoimen — Wed, 19 May 2010 14:14:03 +0000

No PHP programmer writes code without arrays. Sound strange, but as many programmers there are, as many ways to format the array notation there are.

My advice is to rely on a defined standard. I personally use the Zend Framework’s coding style.

So how to format the code? The first way is on the same line:

$myArray = array('key1' => 'value1',
		 'key2' => 'value2');

And the other, perhaps more clear way is to place the associative pairs on a new line:

$myArray = array(
	'key1' => 'value1',
	'key2' => 'value2',
);

Note that in the second example there’s a comma after the second pair. This is correct PHP syntax and is strongly encouraged!

It’s up to you which way to take. However it mainly depends on the case, but please use standards.

PHP: The Array Element Doesn’t Exist – Suppress the Warnings

Stoimen — Mon, 17 May 2010 16:54:23 +0000

What’s the problem?

If you code PHP from couple of hours you are probably familiar with the following problem:

The first and most common solution is just by adding the isset() statement and the code will look like that:

However do you know there’s is another simple and elegant solution? Simply add the @ sign to suppress the element existence

HTML Tag Semantics. STRONG vs. B!

Stoimen — Thu, 11 Mar 2010 12:09:17 +0000

Do You Use LABEL?

Have you ever mentioned the existence of the LABEL tag? Have you ever used it? I guess the majority of us don’t. Let’s take a look of the following chunk of code:

username:

It looks familiar to every web developer, but the most common usage in web forms is:

username:

username:

How Looks a LABEL Tag?

In fact if you use LABEL for the form instead of DIV or SPAN you’ll get the exactly same result as layout, beside that most common usage is a DIV or SPAN in place of the forgotten LABEL?! Why is that?

Can you see the difference between LABEL and SPAN?

For me the usage of DIV has become critically enormous. It may sound strange that there is a debate about the usage of one or another HTML tag, but don’t you think every little text label in a web project is surrounded by a DIV. Actually that makes clear that if you’d like to be semantically correct, than you should use LABEL.

The funny thing is that almost every project is loading its labels in a PHP array or object or whatever and there they are called “Labels”, but when it comes to HTML they are put into a DIVs.

Why Semantics Matters?

In fact this is important because this is really good for web robots. If this is not important for the human eye it is for a machine “eye”. That’s why there are two tags for bold text.

STRONG vs. B

You can see that most of the browsers display both tags exactly the same by default.

Why’s that? Because STRONG is semantically more important than .

So if you want to make a text simply looking bold, wrap it in , but if you want to make it important both for the human eye and for the machines, than use STRONG.

Source: complete demo.

Related posts:

2xjQuery: Select a Selector

Faster HTML! Why not?

Fast way to manage the Arabic version of a web form

PHP if-else-endif Statements