Monthly Archives: January 2022

Learning PHP The Right Way vol 2

Notes for myself from youtube tutorial Full PHP 8 Tutorial - Learn PHP The Right Way by Program With Gio. Video nr 4: What Are Constants & Variable Variables In PHP - Full PHP 8 Tutorial

Constants - we can't overwrite values. Constants are defined using uppercase. There are two ways of defining constants:
- define('name', 'value');
```
<?php define ('STATUS_PASSED', 1);
echo SATUS_PASSED
?>
```
  or
```
<?php 
$passed = 1;
define('STATUS_'.$passed, 1);
echo STATUS_PAID
?>
```
  returns
```
1
```
  This function is defined at a runtime and can be used in control structures - if true then define('HEALTH', 'ok').
- const
```
<?php
    const STATUS_PASSED=1;
    echo STATUS_PASSED
?>
```
  It is defined during compile time, it means can't use it in loops and if /else.
To find out if the constant is defined, we can use:
```
<?php
    echo defined('STATUS_PASSED')
    ?>
```
It returns boolean. If it returns 1, the constant is defined.
Magical constants are this:
```
<?php   
echo __LINE__ (two underscores);
?>
```
Their value depends where they are used.
Variable variables $$a- takes the variable's value and treats it as the name of the new variable.
```
<?php  
$a = "capital";
```
$$a
```
 = "city";
echo $a.$capital  //returns "capitalcity"
?>
```
Variable variables can be also printed out like this:
```
<?php
echo $a.$a;
echo "$a.{$a}";
echo "$a.${$a}"
?>
```

Learning PHP The Right Way vol 1

Notes for myself from youtube tutorial Full PHP 8 Tutorial - Learn PHP The Right Way by Program With Gio. Video nr 3: Basic PHP Syntax - PHP 8 Tutorial

If the file contains only php code, there is no need to add the final
```
?>
```
ending.
There is no need for ending semicolon if:
- it is the only line between php-tags
```
<?php echo "Hello" ?>
```
- it is the last line of the file before ending
```
?>
```
  tag.
echo is faster than print and latter returns value 1
```
<?php echo print "Hello"?>
```
returns
```
Hello1
```
$this refers to object, so you can't get it as a variable's name.
Variables can be sign as reference—if value changes, you change too!
```
<?php 
$x = 3;
$z=&$x; 
$x=1;
echo $z
?>
```
returns
```
1
```