PHP for Loop

Last update on May 28 2022 12:33:34 (UTC/GMT +8 hours)

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

php 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:

View the example in the browser

Previous: do-while statement
Next: foreach statement

PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC