PHP Exercises: Create a new string where 'if' is added to the front of a given string
PHP Basic Algorithm: Exercise-5 with Solution
Write a PHP program to create a new string where 'if' is added to the front of a given string. If the string already begins with 'if', return the string unchanged.
Sample Solution:
PHP Code :
<?php
function test($s)
{
if (strlen($s) >= 2 && substr($s,0, 2) == "if")
{
return $s;
}
return "if ".$s;
}
echo test("if else")."\n";
echo test("else")."\n";
echo test("if")."\n";
Sample Output:
if else if else if
Flowchart:
PHP Code Editor:
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Previous: Write a PHP program to check a given integer and return true if it is within 10 of 100 or 200.
Next: Write a PHP program to remove the character in a given position of a given string. The given position will be in the range 0..string length -1 inclusive.
What is the difficulty level of this exercise?
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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
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