[Class] How to code PHP 101

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How to code PHP 101



Today, I would like to introduce everybody to my first tutorial here, I'm not sure if this is allowed but I'm going to go for it. I will be posting tutorials as I go along.


Where To Start Programming PHP

To begin programming PHP, I recommend learning how to code HTML first. PHP depends on HTML for input and other functions. If you have already learnt HTML, you should already have a code editor. (WYSIWYG editors may or may not have this feature) Normally PHP is only put on pages with the extension .php, but if the server is configured correctly you will be able to use it on extensions like .html and .htm. PHP stands for PHP: Hypertext Preprocessor. All php code starts with:

Code:

Although, this is not required if you have only php code on a page, or you are at the end of the page and putting some more code :P

Commenting PHP

In HTML to create a comment you would use

Code:

Whilst in php there are two types of comments, the single line and multi line, an example of a singe line comment:

Code:

The other way of commenting with single lines is:

Code:

To do a multi line comment:

Code:

Comments can be used anywhere and cannot be seen by users like HTML comments.

Variables

Unlike some other programming languages you may have learnt/used, PHP does not require their variables to be initialized before usage. Java Example:

Code:

int var;
var = 1;

PHP Example:

Code:

$var = 1;

There are many types of variables, but let's start with the three most basic types of variables; integers, booleans and strings. There are distinct differences between the three, like integers are only whole numbers. (no decimals, use float instead) Booleans are either true or false, but nothing else, and strings are simply anything you can type. Here are some examples, here is a integer:

Code:

$var = 1;

Here is a boolean:

Code:

$var = true;

Finally a string:

Code:

$var = "Hello";

A variable can be any type and the types are interchangeable. Unlike Java, where a variable could only be one type. You can make sure a variable is only one type, try using this example:

Code:

$var = (int) 1;

But after that line the $var can be changed to anything unless the (int) stays every time you change the variable.

Showing Information in the Browser with PHP

PHP has many ways of showing information, the most used, would be echo, it is not technically a function, but anyway, echo will write anything to the user's browser. An example of echo:

Code:

You can also use variable when echoing information, there are two ways, first way:

Code:

Or you could use this:

Code:

In place of echo (print should work in every place that echo works) you could use print like this:

Code:

To dump a variable, use either print_r or var_dump like this:

Code:

or with var_dump:

Code:

Loops

There are many ways in PHP to write code, but most likely loops are used for their flexibility and simplicity. There are many different types of loops for difference purposes.

The if/elseif/else loop:

Code:

if (condition)
{
Execute only if it meets the condition
}
else if (condition)
{
Execute only if it meets the condition and doesn't meet the previous condition
}
else
{
Execute only if it doesn't meet any of the previous condition(s)
}

NOTE: You can remove the (else if/else) if it isn't required in your code.

The for loop:

Code:

for (define variable;condition;execute after executing the code in the loop)
{
Execute only if it meets the condition
}

The foreach loop:

Code:

foreach (variable1 as variable2)
{
Execute for every variable in the array in variable1 but use variable2 to refer to the current variable in the array in variable1
}

The switch loop:

Code:

switch (variable)
{
case 'random':
Execute this code only if variable is equal to random
break;

case 'irregular':
Execute this code only if variable is equal to irregular
break;

default:
Execute this code only if variable is not equal to any of the previous option(s).
break;
}