'const' vs. 'static' in PHP [duplicate]

Question

In PHP 5 I can declare a const value to a class:

class config
{
     const mailserver = 'mx.google.com';
}

But I can also declare public static:

class config
{
     public static $mailserver = 'mx.google.com';
}

In case of a configuration file which I will later use, like:

imap_connect(config::$mailserver ...
imap_connect(config::mailserver ...

Which of the options do you think is better to be used? (Faster, less memory load, etc...)

Answer 1

The static variable can be changed, the const one cannot. The main consideration should be given to whether the config variables should be able to be altered at run time, not which is faster. The speed difference between the two (if there is any) is so minimal it isn't worth thinking about.

Answer 2

use function return global

0.0096, 0.0053, 0.0056, 0.0054, 0.0072, 0.0063, 0.006, 0.0054, 0.0054, 0.0055, 0.005, 0.0057, 0.0053, 0.0049, 0.0064, 0.0054, 0.0053, 0.0053, 0.0061, 0.0059, 0.0076, config1

use get instance normal class

0.0101, 0.0089, 0.0105, 0.0088, 0.0107, 0.0083, 0.0094, 0.0081, 0.0106, 0.0093, 0.0098, 0.0092, 0.009, 0.0087, 0.0087, 0.0093, 0.0095, 0.0101, 0.0086, 0.0088, 0.0082, config2

use static var

0.0029, 0.003, 0.003, 0.0029, 0.0029, 0.0029, 0.003, 0.0029, 0.003, 0.0031, 0.0032, 0.0031, 0.0029, 0.0029, 0.0029, 0.0029, 0.0031, 0.0029, 0.0029, 0.0029, 0.0029, config3

use const var 0.0033, 0.0031, 0.0031, 0.0031, 0.0031, 0.0031, 0.0032, 0.0031, 0.0031, 0.0031, 0.0031, 0.0034, 0.0031, 0.0031, 0.0033, 0.0031, 0.0037, 0.0031, 0.0031, 0.0032, 0.0031, config4

function getTime() { 
    $timer = explode( ' ', microtime() ); 
    $timer = $timer[1] + $timer[0]; 
    return $timer; 
}

$config["time"] = "time";

class testconfig2
{
    public  $time = "time";
    static $instance;
    static function getInstance()
    {
        if(!isset(self::$instance))
            self::$instance = new testconfig2();
        return self::$instance;
    }
}

class testconfig3
{
    static $time = "time";
}

class testconfig4
{
    const time = "time";
}

function getConfig1()
{
    global $config;
    return $config;
}

$burncount = 2000;
$bcount = 22;

for($lcnt =1;$lcnt < $bcount;$lcnt++){
$start = getTime(); 
for($i=1;$i< $burncount;$i++)
{
    $gs=getConfig1();
    $t = $gs["time"];
} 
$end = getTime(); 
echo  round($end - $start,4).', ';
}
echo  ' config1<br/>';



for($lcnt =1;$lcnt < $bcount;$lcnt++){
$start = getTime(); 
for($i=1;$i< $burncount;$i++)
{
    $gs=testconfig2::getInstance();
    $t = $gs->time;
} 
$end = getTime(); 
echo  round($end - $start,4).', ';
}
echo  ' config2<br/>';



for($lcnt =1;$lcnt < $bcount;$lcnt++){
$start = getTime(); 
for($i=1;$i< $burncount;$i++)
{
    $gs=testconfig3::$time;
    $t = $gs;
} 
$end = getTime(); 
echo  round($end - $start,4).', ';
}
echo  ' config3<br/>';



for($lcnt =1;$lcnt < $bcount;$lcnt++){
$start = getTime(); 
for($i=1;$i< $burncount;$i++)
{
    $gs=testconfig4::time;
    $t = $gs;
} 
$end = getTime(); 
echo  round($end - $start,4).', ';
}
echo  ' config4<br/>';
?>