PHP for Loop
Description
The PHP for loop allows the user to put all the loop-related statements (i.e. INITIALIZER; CONDITION; INCREMENTOR or DECREMENTOR) in one place. The structure is similar to C language.
Syntax
for ( initialize counter ; test counter ; increment counter) { execute the statement; }
- initialize counter : Initialize the loop counter value.
- test counter : Verify the loop counter whether the condition is true.
- increment counter : Increasing the loop counter value.
- execute the statement : Execute php statements.
Alternatively, you can write for loop statement using the following syntax also.
for (expr1; expr2; expr3): statement ... endfor;
Pictorial representation of for loop
Example:
The following example displays the numbers between 0 to 5.
<?php
for ($xint=0; $xint<=5; $xint++)
{
echo "Number is : $xint <br />";
}
?>
Output:
Number is : 0 Number is : 1 Number is : 2 Number is : 3 Number is : 4 Number is : 5
View the example in the browser
You can execute for in the following ways also.
<?php
for ($xint = 1; ; $xint++) {
if ($i >= 5) {
break;
}
echo $xint;
}
?>
<?php
$xint = 1;
for (; ; )
{
if ($xint >= 5)
{
break;
}
echo $xint;
$xint++;
}
?>
Example: Counting number of times a word present in a sentence.
<?php
$text="The quick brown Fox jumps over the lazy Dog";
$words = explode(" ", $text); // explode function looks for " " and creates an array, where each word is an element of the array
$now = count($words);
$j = 0;
for($i=0; $i<$now; $i++)
{
if ($words[$i] == "the" or $words[$i] == "The")
{
$j = $j+1;
}
}
echo $j;
?>
Output:
2
View the example in the browser
Previous: do-while statement
Next: foreach statement
PHP: Tips of the Day
Members of objects or classes can be accessed using the object operator (->) and the class operator (::).
Example:
class MyClass { public $a = 1; public static $b = 2; const C = 3; public function d() { return 4; } public static function e() { return 5; } } $object = new MyClass(); var_dump($object->a); // int(1) var_dump($object::$b); // int(2) var_dump($object::C); // int(3) var_dump(MyClass::$b); // int(2) var_dump(MyClass::C); // int(3) var_dump($object->d()); // int(4) var_dump($object::d()); // int(4) var_dump(MyClass::e()); // int(5) $classname = "MyClass"; var_dump($classname::e()); // also works! int(5)
Note that after the object operator, the $ should not be written ($object->a instead of $object->$a). For the class operator, this is not the case and the $ is necessary. For a constant defined in the class, the $ is never used.
Also note that var_dump(MyClass::d()); is only allowed if the function d() does not reference the object:
class MyClass { private $a = 1; public function d() { return $this->a; } } $object = new MyClass(); var_dump(MyClass::d()); // Error!
This causes a 'PHP Fatal error: Uncaught Error: Using $this when not in object context'
These operators have left associativity, which can be used for 'chaining':
class MyClass { private $a = 1; public function add(int $a) { $this->a += $a; return $this; } public function get() { return $this->a; } } $object = new MyClass(); var_dump($object->add(4)->get()); // int(5)
These operators have the highest precedence (they are not even mentioned in the manual), even higher that clone. Thus:
class MyClass { private $a = 0; public function add(int $a) { $this->a += $a; return $this; } public function get() { return $this->a; } } $o1 = new MyClass(); $o2 = clone $o1->add(2); var_dump($o1->get()); // int(2) var_dump($o2->get()); // int(2)
The value of $o1 is added to before the object is cloned!
Note that using parentheses to influence precedence did not work in PHP version 5 and older (it does in PHP 7):
// using the class MyClass from the previous code $o1 = new MyClass(); $o2 = (clone $o1)->add(2); // Error in PHP 5 and before, fine in PHP 7 var_dump($o1->get()); // int(0) in PHP 7 var_dump($o2->get()); // int(2) in PHP 7
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