Introductie van PHP-trefwoorden

Sleutelwoorden zijn de woorden die een betekenis hebben. Bij regelmatig gebruik van de PHP-taal kunnen deze woorden niet worden gebruikt als een constante, een variabelenaam, een methodenaam, een klassenaam, enz. Deze trefwoorden worden bij gebruik automatisch begrepen door PHP. Deze PHP-sleutelwoorden, wanneer gebruikt met variabelenamen, kunnen worden verward met de eigenlijke sleutelwoorden. Daarom moeten deze trefwoorden niet worden gebruikt als variabelenamen.

Lijst met alle PHP-trefwoorden

Trefwoord: abstract

Code:

<_?php
//example to demonstrate abstract keyword
abstract class Program (
abstract protected function MethodOne();
public function display() (
echo '
'.$this->MethodOne();
)
)
class ProgramOne extends Program (
protected function MethodOne() (
echo '
'.'In MethodOne';
)
)
$objOne = new ProgramOne;
$objOne->display();
?>,

Output:

Trefwoord: en

Code:

<_?php
//example to demonstrate and keyword
$a = 10;
$b = 11;
if($a ==10 and $b == 11) (
echo 'Result : True';
)
else
(
echo 'Result : False';
)
?>

Output:

Trefwoord: array ()

Code:

<_?php
//example to demonstrate array keyword
$directions = array("e" => "east", "w" => "west", "n" => "north", "s" => "south");
print_r($directions);
?>

Output:

Trefwoord: as

Code:

<_?php
//example to demonstrate array keyword
$directions = array("e" => "east", "w" => "west", "n" => "north", "s" => "south");
foreach($directions as $key=>$value) (
echo '
'. $key. '=>'.$value;
)
?>

Output:

Trefwoord: pauze

Code:

<_?php
//use of break keyword without optional argument
$arr = array("water", "sky", "try", "sand");
foreach($arr as $key=>$value) (
if($value == 'try') (
break ; // can use break 1 also
)
echo '
'.$value;
)
?>

Output:

Trefwoord: case

Code:

<_?php
//example to demonstrate case keyword
$i = 1;
while($i<5) (
switch($i) (
case 1:
echo "
"."One";
break;
case 2:
echo "
"."Two";
break;
case 3:
echo "
"."Three";
break;
default:
echo "
"."Default";
)
$i++;
)
?>

Output:

Trefwoord: vangen

Code:

<_?php
//example to demonstrate catch keyword
function Operation()
(
try (
$num1 = 10;
$num2 = 0;
if($num1 / $num2) (
throw new Exception('Divide By Zero');
)
) catch (Exception $e) (
die($e->getMessage());
)
)
Operation();
?>

Output:

Trefwoord: klasse

Code:

<_?php
//example to demonstrate class keyword
class ClassOne(
var $str = 'Hello World';
public function displayMethod() (
echo $this->str;
)
)
$obj = new ClassOne;
$obj->displayMethod();
?>

Output:

Trefwoord: const

het sleutelwoord const wordt gebruikt om de naam met een waarde te definiëren met behulp van een toewijzingsoperator zoals hieronder

const LEEFTIJD = 29;

Er is geen $ -teken aan het begin van een constante naam zoals een normale variabele heeft.

Trefwoord: standaard

Code:

<_?php
// example to demonstrate default keyword
$fruits = 'Cherries';
switch ($fruits) (
case 'Apple':
echo "Apple";
break;
case 'Banana':
echo "Banana";
break;
case 'Papaya':
echo "Papaya";
break;
default:
echo "Fruit is not Apple, Banana or Papaya ";
break;
)
?>

Uitgang:

Trefwoord: doen

Code:

<_?php
// example to demonstrate do keyword
$x = 2;
do (
if($x > 2)
(
echo 'x is greater than 2';
)
else(
echo 'x is less than 2';
)
) while ($x < 2);
?>

Output:

Trefwoord: die ();

Code:

<_?php
//example to demonstrate die keyword
$conn = mysqli_connect('localhost', 'root', '', 'dbname');
if(!$conn) (
die("Unable to connect ");
)
?>

Output:

Trefwoord: echo

Code:

<_?php
// example to demonstrate echo keyword
echo 'Hello! ';
$name = 'John Doe';
echo 'My name is '. $name;
?>

Output:

Trefwoord: anders

Code:

<_?php
// example to demonstrate else keyword
$a = 10;
if ($a > 5) (
echo "a is greater than 10";
) else (
echo "a is not greater than 10";
)
?>

Output:

Trefwoord: elseif

Code:

<_?php
// example to demonstrate elseif keyword
$a = 10;
if ($a > 10) (
echo "a is greater than 10";
) elseif ($a == 10) (
echo "a is equal to 10";
) else (
echo "a is smaller than 10";
)
?>

Uitgang:

Trefwoord: leeg

Code:

<_?php
// example to demonstrate empty keyword
$str = 'Hello World!';
if(empty($str)) (
echo 'Variable is empty';
) else (
echo $str;
)
?>

Output:

Trefwoord: endfor

Code:

<_?php
// example to demonstrate endfor keyword
for($i=0;$i<5;$i++) :
echo "
".$i;
endfor;
?>

Output:

Trefwoord: endif

Code:

<_?php
// example to demonstrate endif keyword
if ($a > 10):
echo "a is greater than 10";
elseif ($a >10) :
echo "a is equal to 10";
else:
echo "a is not equal to 10";
endif;
?>

Output:

Trefwoord: endforeach

Code:

<_?php
// example to demonstrate endforeach keyword
$arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
foreach ($arr as $key=>$value):
echo '
'.$value;
endforeach;
?>

Output:

Trefwoord: eindschakelaar

Code:

<_?php
// example to demonstrate endswitch keyword
$fruits = 'Cherries';
switch ($fruits):
case 'Apple':
echo "Apple";
break;
case 'Banana':
echo "Banana";
break;
case 'Papaya':
echo "Papaya";
break;
default:
echo "Fruit is not Apple, Banana or Papaya ";
break;
endswitch;
?>

Output:

Trefwoord: eindtijdig

Code:

<_?php
// example to demonstrate endwhile keyword
$i = 0;
while($i<5):
echo "
".$i;
$i++;
endwhile;
?>

Output:

Trefwoord: eval ()

Code:

<_?php
//example to demonstrate eval keyword
$string1 = 'World';
$string2 = 'John Doe';
$string = 'Hello $string1 . My name is $string2';
echo "
".$string;
eval("\$string = \"$string\";");
echo "
".$string;
?>

Output:

Trefwoord: exit ()

Wanneer dit trefwoord in een script wordt aangetroffen, wordt de uitvoering van het script beëindigd.

Zoekwoord: verlengt ()

Code:

<_?php
//example to demonstrate extends keyword
class ParentClass (
var $string = 'PHP';
public function display() (
echo $this->string;
)
)
class ExtendClass extends ParentClass (
public function display() (
echo 'Hello World!';
)
)
$obj1 = new ExtendClass;
$obj1->display();
?>

Output:

Trefwoord: definitief

Code:

<_?php
//example to demonstrate final keyword
class ParentClass (
var $string = 'PHP';
final public function display() (
echo $this->string;
)
)
class ExtendClass extends ParentClass (
public function display() (
echo 'Hello World!';
)
)
$obj1 = new ExtendClass;
$obj1->display();
?>

Uitgang:

Trefwoord: vangen

Code:

<_?php
//example to demonstrate catch keyword
try (
$num1 = 10;
$num2 = 0;
if($num1 / $num2) (
throw new Exception('Divide By Zero');
)
) catch (Exception $e) (
echo '
'.$e->getMessage();
)
?>

Output:

Trefwoord: voor

Code:

<_?php
// example to demonstrate for keyword
for($i=0; $i<10; $i++) (
if($i == 5) (
break;
)
echo '
'.$i;
)
?>

Uitgang:

Trefwoord: foreach

Code:

<_?php
// example to demonstrate foreach keyword
$array = array(10, 20, 30, 40, 50);
foreach($array as $value) (
echo '
'.$value/10;
)
?>

Output:

Trefwoord: functie ()

Code:

<_?php
function calSum($a, $b) (
$c = $a + $b;
return $c;
)
$result = calSum(10, 20);
echo '
The sum : '.$result;
?>

Output:

Trefwoord 34: wereldwijd

Code:

<_?php
//example to demonstrate global keyword
$a = 10;
$b = 20;
function fun() (
global $a;
global $b;
$result = $a + $b;
return $result;
)
$f = fun();
echo 'The result is '.$f;
?>

Output:

Trefwoord: als

Code:

<_?php
// example to demonstrate if keyword
$sum = 10;
if($sum == 10) (
echo 'Sum is 10';
) else (
echo 'Sum is not 10';
)
?>

Output:

Trefwoord: werktuigen

Code:

<_?php
//example to demonstrate interface keyword
interface One
(
public function first();
)
class MainClass implements One (
public function first() (
echo 'This is the First function';
)
)
$obj = new MainClass;
echo $obj->first();
?>

Uitgang:

Trefwoord: opnemen

Code:

file.php

<_?php
//example to demonstrate include keyword
$a = 'The Earth';
$b = 'Round';
?>

index.php

<_?php
include 'file.php';
echo $a . ' is '. $b. ' in Shape';
?>

Zoekwoord: include_once

Code:

file.php

<_?php
//example to demonstrate include_once keyword
$a = 'The Earth';
$b = 'Round';
?>

index.php

<_?php
Include_once 'file.php';
echo $a . ' is '. $b. ' in Shape';
?>

Output:

Zoekwoord: instanceOf

Code:

<_?php
//example to demonstrate instanceOf keyword
class MainClass
(
public function MainCLassMethod()(
echo 'Hello World!';
)
)
class ExtendedClass extends MainClass
(
public function ExtendedClassMethod()(
echo 'Have a Nice Day!';
)
)
$obj1 = new ExtendedClass;
var_dump($obj1 instanceOf ExtendedClass);
?>

Output:

Trefwoord: interface

Code:

<_?php
//example to demonstrate interface keyword
interface One
(
public function one();
)
interface Two
(
public function two();
)
class MainClass implements One, Two (
public function one() (
echo '
This is the one function';
)
public function two() (
echo '
This is the two function';
)
)
$obj = new MainClass;
echo $obj->one();
echo $obj->two();
?>

Output:

Trefwoord: isset

Code:

<_?php
//example to demonstrate isset keyword
$stringOne = '';
var_dump(isset($stringOne));
$stringTwo = NULL;
var_dump(isset($stringTwo));
?>

Uitgang:

Trefwoord: lijst

Code:

<_?php
//example to demonstrate list keyword
$names = array('Ram', 'Mohan', 'Raghav');
list($person1, $person2, $person3) = $names;
echo "$person1, $person2 and $person3 are friends";
?>

Output:

Trefwoord: nieuw

Code:

<_?php
//example to demonstrate new keyword
class Student
(
public function score($name, $subject, $marks) (
echo "$name scored $marks marks in $subject";
)
)
$obj = new Student;
$obj->score('Sunil', 'Maths', 90);
?>

Output:

Trefwoord: of

Code:

<_?php
//example to demonstrate or keyword
$a = 10;
$b = 11;
if($a ==10 or $b == 12) (
echo 'Result : True';
)
else
(
echo 'Result : False';
)
?>

Uitgang:

Trefwoord: print

Code:

<_?php
//example to demonstrate print keyword
$str = "PHP Programming";
print($str);
$stringOne = "Shyam, ";
$stringTwo = "How are you?";
print "
"."Hello $stringOne $stringTwo";
?>

Uitgang:

Trefwoord: privé

Code:

<_?php
//example to demonstrate private keyword
class MainClass
(
private $str = 'Private';
function PrivateMethod()
(
echo 'In '. $this->str. ' Method';
)
)
$obj = new MainClass();
$obj->PrivateMethod(); //Shows Private Method
?>

Output:

Trefwoord: openbaar

Code:

<_?php
//example to demonstrate public keyword
class MainClass
(
public $str = 'Public';
function PublicMethod()
(
echo 'In '. $this->str. ' Method';
)
)
$obj = new MainClass();
$obj->PublicMethod(); //Shows Public Method
?>

Output:

Trefwoord: beschermd

Code:

<_?php
//example to demonstrate protected keyword
class MainClass
(
protected $str = 'Protected';
function ProtectedMethod()
(
echo 'In '. $this->str. ' Method';
)
)
$obj = new MainClass();
$obj->ProtectedMethod(); //Shows Protected Method
?>

Output:

Trefwoord: retour

Code:

<_?php
//example to demonstrate return keyword
function sum() (
$a = 10;
$b = 20;
$c = $a +$b;
return $c;
)
$result = sum();
echo 'Sum : ' . $result;
?>

Output:

Trefwoord: schakelaar

Code:

<_?php
//example to demonstrate switch keyword
$i= 3;
switch($i) (
case 1:
echo "
"."One";
break;
case 2:
echo "
"."Two";
break;
case 3:
echo "
"."Three";
break;
default:
echo "
"."Default";
)
?>

Output:

Trefwoord: gooien

Code:

<_?php
//example to demonstrate throw keyword
function division($x, $y) (
try (
if($y == 0) (
throw new Exception('Divide By Zero');
)
)
catch (Exception $e) (
echo '
'.$e->getMessage();
)
)
division(10, 0);
?>

Output:

Trefwoord: probeer

Code:

<_?php
//example to demonstrate try keyword
try(
$arr = array();
$arr_length = count($arr);
if($arr_length == 0) (
throw new Exception('Error : Empty Array!');
)
else (
echo 'Array found';
print_r($arr);
)
)
catch(Exception $e) (
echo '
'.$e->getMessage();
)
?>

Output:

Trefwoord: niet ingesteld

Code:

<_?php
//example to demonstrate unset keyword
echo 'Hello World!'.'
';
$a = 10;
echo $a;
unset($a);
// echo $a; //this line when uncommented shows error : Undefined variable, as the variable is unset
?>

Output:

Trefwoord: var

Code:

<_?php
//example to demonstrate var keyword
class MainClass
(
var $str = 'PHP Programming';
public function displayMsg() (
echo $this->str;
)
)
$obj = new MainClass;
$obj->displayMsg();
?>

Output:

Trefwoord: terwijl

Code:

<_?php
//example to demonstrate while keyword
$i = 0;
while ($i<10) (
echo '
'. $i;
$i++;
)
?>

Output:

Conclusie

In dit artikel leert u over zoekwoorden in PHP met voorbeelden. Deze voorbeelden verklaren het gebruik van elk van de trefwoorden in PHP.

Aanbevolen artikelen

Dit is een handleiding voor de PHP-trefwoorden. Hier bespreken we de inleiding tot PHP-trefwoordenlijst van alle PHP-trefwoorden samen met trefwoorden en outputs. U kunt ook onze andere voorgestelde artikelen doornemen voor meer informatie–

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