Static variables

 <?php

function keep_track() {

 STATIC $count = 0;

 $count++;

 print $count;

 print "<br>";

}

keep_track();

keep_track();

keep_track();

?>

Error reporting

<?php

// -------------------------------

// PHP Error Reporting Example

// -------------------------------

// Report all errors except user warnings and notices

error_reporting(E_ALL & ~E_USER_WARNING & ~E_USER_NOTICE);

// Display errors on screen (for development)

ini_set('display_errors', 1);

// Add a prefix to each error message

ini_set('error_prepend_string', '<strong>Error:</strong> ');

// Example errors

echo $undefined_variable;                 // Notice (ignored)

trigger_error("This is a warning", E_USER_WARNING);  // User warning (ignored)

trigger_error("This is an error", E_USER_ERROR);     // User error (shown with prefix)

?>

 $options = array(

    CURLOPT_URL => 'http://www.example.com/',

    CURLOPT_RETURNTRANSFER => true,  // boolean

    CURLOPT_HEADER => false,         // boolean

    CURLOPT_USERAGENT => ''          // empty string, will be filtered

);

// Filter only non-empty strings

$options = array_filter($options, fn($v) => gettype($v) === 'string' && strlen($v) > 0);

$ch = curl_init();

foreach($options as $opt => $val){

    curl_setopt($ch, $opt, $val);

}

$response = curl_exec($ch);

curl_close($ch);

curl

<?php
// Create a curl handle to a non-existing location
$ch = curl_init('http://404.php.net/');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);


if(curl_exec($ch) === false)
{
echo 'Curl error: ' . curl_error($ch);
}
else
{
echo 'Operation completed without any errors';


}

//echo $error =( curl_errno($ch)>0)?curl_error($ch).", error code :  ".curl_errno($ch):"All good";

?>

https://www.php.net/manual/en/langref.php

 https://www.php.net/manual/en/langref.php

Array map

 <?php

function cube($n, $r)

{

    return ($n * $n * $n) / $r;

}

$a = [1, 2, 3, 4, 5];

$c = [1, 2, 3, 4, 5];

$b = array_map('cube', $a, $c);

print_r($b);

?>

array filter

 $arr=[12,3,90,4];

function Myfunc($k){

return $k>80;

}

$result=array_filter($arr,"Myfunc",0);

  

  print_r($result);