PHP must known basics

PHP printing command, echo. These 3 lines print the same string “Hello World!”

echo "Hello World!";
echo "Hello "."World!";
echo "Hello ","World!";

PHP configuration information. This phpinfo() function will returen all the PHP configuratoin on your server.

echo phpinfo();

PHP interactive command console. This terminal command will bring you to the php interactive command console where you can execute php code on the fly. Ctrl-C to exit.

php -a

PHP var_dump, this function displays structured information about one or more expressions that includes its type and value. Arrays and objects are explored recursively with values indented to show structure.

$scores = array(
	'Amy'	=> array('english'=>90,'math'=>95,'biology'=>92,'physics'=>'97'),
	'Ben'	=> array('english'=>93,'math'=>91,'biology'=>94,'physics'=>'99'),
	'Chery'	=> array('english'=>92,'math'=>96,'biology'=>90,'physics'=>'92')
	);
var_dump($scores);

PHP print_r, similary to var_dump, but it will present the information of a variable in a more human readable way.

$scores = array(
	'Amy'	=> array('english'=>90,'math'=>95,'biology'=>92,'physics'=>'97'),
	'Ben'	=> array('english'=>93,'math'=>91,'biology'=>94,'physics'=>'99'),
	'Chery'	=> array('english'=>92,'math'=>96,'biology'=>90,'physics'=>'92')
	);
print_r($scores);

PHP get the class name and class methods of an object.

echo get_class($e);
echo print_r(get_class_methods($e));

PHP dump all session variables.

var_dump($_SESSION);

PHP die() and exit(), stops the execution of the script.

die("stop here");
die(var_dump($somevar));
exit("stop here");
exit(var_dump($somevar));

PHP array.

$fruits = array('apple','banana','cherry');

PHP associative array.

$scores = array('Amy'=>95,'Ben'=>92,'Chery'=>98,'Dan'=>96);

PHP nested array.

$scores = array(
	'Amy'	=> array('english'=>90,'math'=>95,'biology'=>92,'physics'=>'97'),
	'Ben'	=> array('english'=>93,'math'=>91,'biology'=>94,'physics'=>'99'),
	'Chery'	=> array('english'=>92,'math'=>96,'biology'=>90,'physics'=>'92')
	);

PHP foreach loop.

$fruits = array('apple','banana','cherry');
foreach($fruits as $f)
{
	echo $f;
}

$scores = array(
	'Amy'	=> array('english'=>90,'math'=>95,'biology'=>92,'physics'=>'97'),
	'Ben'	=> array('english'=>93,'math'=>91,'biology'=>94,'physics'=>'99'),
	'Chery'	=> array('english'=>92,'math'=>96,'biology'=>90,'physics'=>'92')
	);
foreach($scores as $name => $subs)
{
	echo $name."\n<br>";
	foreach($subs as $sub => $score)
	{
		echo $sub . ": ". $score." ";
	}
	echo "\n<br>";
}

PHP for loop.

$fruits = array('apple','banana','cherry');
for($i=0; $i<count($fruits); $i++)
{
	echo $fruits[$i]." \n<br>";
}

PHP while loop.

$fruits = array('apple','banana','cherry');
$size = count($fruits);
$i=0;
while($i<$size)
{
	echo $fruits[$i]." \n<br>";
	$i++;
}

PHP if else statements.

$num = rand(0,10); // generate a random number from 0 to 10 inclusive
if($num==0) echo $num . " is zero.";
else if($num%2 ==0) echo $num . " is an even number.";
else echo $num . " is an odd number.";

PHP class definition.

class Person
{
	public $name;
	public $age;

	function __construct($name, $age)
	{
		$this->name = $name;
		$this->age = $age;
	}

	public function speak()
	{
		echo "Hello, my name is ".$this->name.", I am ".$this->age." years old.";
	}

}

$p = new Person("Amy",18);
$p->speak();

PHP inheritance.

class Employee extends Person
{
	public $career;
	function __construct($name, $age, $career)
	{
		parent::__construct($name, $age);
		$this->career = $career;
	}

	//override the parent speak.
	public function speak()
	{
		parent::speak();
		echo "My career is " . $this->career; 
	}
}
$e = new Employee('Ben',22,'Programmer');
$e->speak();

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