Tag Archives: php tutorial

Some Notes on the Object-oriented Model of PHP

PHP 5 introduces interfaces and abstract classes. To become a little clearer, let us see their definitions.


Object interfaces allow you to create code which specifies which methods a class must implement, without having to define how these methods are handled.
Interfaces are defined using the interface keyword, in the same way as a standard class, but without any of the methods having their contents defined.
All methods declared in an interface must be public, this is the nature of an interface.

To implement an interface, the implements operator is used. All methods in the interface must be implemented within a class; failure to do so will result in a fatal error. Classes may implement more than one interface if desired by separating each interface with a comma.

Abstract Classes

PHP 5 introduces abstract classes and methods. Classes defined as abstract may not be instantiated, and any class that contains at least one abstract method must also be abstract. Methods defined as abstract simply declare the method’s signature – they cannot define the implementation.

When inheriting from an abstract class, all methods marked abstract in the parent’s class declaration must be defined by the child; additionally, these methods must be defined with the same (or a less restricted) visibility. For example, if the abstract method is defined as protected, the function implementation must be defined as either protected or public, but not private. Furthermore the signatures of the methods must match, i.e. the type hints and the number of required arguments must be the same. This also applies to constructors as of PHP 5.4. Before 5.4 constructor signatures could differ.

Some Cases

Now let’s do a quick experiment. According to the definition of interfaces we can define an interface and than an abstract class can implement this interface.
Continue reading Some Notes on the Object-oriented Model of PHP

Thing to Know About PHP Arrays

Consider the following case. We have an array with identical keys.

$arr = array(1 => 10, 1 => 11);

What happens when the interpreter reaches this line of code? This is not a syntax error and it is completely valid. Very similar, but more interesting case is when we have an array of identical keys, where those identical keys are represented once as an integer and then as a string.

Keys in PHP arrays are not type sensitive, so pay attention when using them!
Keys in PHP arrays are not type sensitive, so pay attention when using them!

$arr = array(1 => 10, "1" => 11);

Now several questions arise. First of all, how many elements have this array? Two or one. This can be easily verified by checking what count() will return. Continue reading Thing to Know About PHP Arrays

5 PHP String Functions You Need to Know

Strings in PHP

The Task

First of all what we’d like to achieve? The task is to convert a string, most of the cases single word, by capitalize the first letter. In my case I’ve the world countries names all lower cased, while I need them with first letter capitalized. In example “united states” must become “United States”, but not “United states” or “UNITED STATES”. So here began the journey into PHP string functions, especially those for capitalization!

1. ucwords

The first thing you find in the PHP Manual is the ucwords function. It changes the first letter to a capital letter, but it does not do the job. Why? Well let me show you an example.

$str1 = 'foo bar';
$str2 = 'Foo bar';
$str3 = 'FOO BAR';
$str4 = 'фуу бар';
echo ucwords($str1); // Foo Bar
echo ucwords($str2); // Foo Bar
echo ucwords($str3); // FOO BAR
echo ucwords($str4); // фуу бар

Here we have four strings. A lower cased, an upper cased, a mixed cased and … a lower cased Cyrillic string. First of all the main reason why ucwords doesn’t fit here is because of the Cyrillic string. Whatever non-Latin string you have you can forget about capitalization. However the other strings conversions are also interesting. Take a look at the third string! Here the string remains “FOO BAR” instead of going “Foo Bar”, which simply means that this function only looks, and hopefully changes, the first letter.

So here we have two questions. How can we overcome the Cyrillic problem and how to “normalize” the UPPER CASE string?

2. ucfirst

This is another useful function in PHP. ucfirst as you may guess from its name converts a string by only changing its first letter. So “Foo bar” will remain “Foo bar”, while with ucwords it has become “Foo Bar”. Let’s see what this function does:

$str1 = 'foo bar';
$str2 = 'Foo bar';
$str3 = 'FOO BAR';
$str4 = 'фуу бар';
echo ucfirst($str1); // Foo bar
echo ucfirst($str2); // Foo bar
echo ucfirst($str3); // FOO BAR
echo ucfirst($str4); // фуу бар

Here even the first string has only one capital letter – “foo bar” became “Foo bar”, and yet again we’ve the Cyrillic string unchanged. It simply doesn’t help us here!

3. mb_convert_case

As a PHP developer you know what the “mb_” prefix means – multibyte. This is quite useful. You can convert the string whatever the encoding is, so perhaps we can overcome the Cyrillic problem. But before proceeding to tests, let’s take a look at the parameters of this function.

The first thing to note here is that mb_convert_case doesn’t contain the case in its name – upper or lower. There’s a second parameter, after the first which is the string itself, who setups that. Note that here you don’t have the typical camel case or capitals parameter name, but MB_CASE_TITLE (as you know in English the title is always capitalized):

echo mb_convert_case($str, MB_CASE_TITLE, ...

And a third one which specifies the encoding:

echo mb_convert_case($str, MB_CASE_TITLE, 'utf-8')

Now let’s see what we can achieve with it:

$str1 = 'foo bar';
$str2 = 'Foo bar';
$str3 = 'FOO BAR';
$str4 = 'фуу бар';
echo mb_convert_case($str1, MB_CASE_TITLE, 'utf-8'); // Foo Bar
echo mb_convert_case($str2, MB_CASE_TITLE, 'utf-8'); // Foo Bar
echo mb_convert_case($str3, MB_CASE_TITLE, 'utf-8'); // Foo Bar
echo mb_convert_case($str4, MB_CASE_TITLE, 'utf-8'); // Фуу Бар

As you can see now the Cyrillic problem doesn’t exists and mb_convert_case is intelligent enough to change “FOO BAR” into “Foo Bar” – as I said this is the English style titling. That is by no means the solution when you deal with capitalization with different encoding.

However there is another approach to overcome the all UPPER CASE conversion problem. A possible solution is to convert the string first to a lower case string.

4. strtolower

strtolower is very useful PHP string function and perhaps any PHP developer has used it at least once. But yet again – it does not do the job. Again because of the encoding problem.

echo strtolower('ФУУ БАР'); // #*&$(#*%#

As you can see the Cyrillic string cannot be lower cased! Let’s search again into the “mb_” universe.

5. mb_strtolower

This is the function. Again you’ve to specify the encoding:

echo mb_strtolower('ФУУ БАР', 'utf-8')


It doesn’t matter whether you’re native English speaker or not. Most of the web sites are multilingual and you cannot be sure what happens when you convert strings in Alphabets different from the Latin. Thus be careful even when everything seems to be OK with Latin string tests.

Automatically Upload Images with PHP Directly from the URI

It is a simple task to upload images on the server with PHP using a simple web form. Than everything’s in the $_FILES array and after submitting the form the file’s on the server. By simply move_uploaded_file you can change its location on the server to the desired folder.

However is there a way to “upload” files without using a web form, but only by telling the PHP script where to find the image. First and most important the image should be web visible and accessible by HTTP.

The solution is quite easy – you can grab the file using file_get_contents, and than put it on the desired server folder with file_put_contents. Here’s some source:

$image = file_get_contents('http://www.example.com/image.jpg');
file_put_contents('/var/www/my.jpg', $image);

Extending the Case

You can go even further by downloading any kind of files with the same approach. What will be the case for an mp4 video is shown in the next example:

$video = file_get_contents('http://www.example.com/video.mp4');
file_put_contents('/var/www/my.mp4', $video);


This can be quite useful when trying to automate an remote upload process. In this case when somebody uploads an image on his site, you can duplicate this file on your server! However don’t forget the copyrights!