Detailed explanation of simple performance test code examples for php7

class PerformanceTest
{
    private $time;
    private $memory;
    public function begin()
    {
        $this->time = $this->getTime();
        $this->memory = $this->getMemory();
    }
    public function end()
    {
        $this->time   = $this->getTime()   - $this->time;
        $this->time   = round($this->time,7);//在这里才能格式化时间
        $this->memory = $this->getMemory() - $this->memory;
        $this->memory = $this->convert($this->memory);
        echo "time:{$this->time}秒<br />";
        echo "memory:{$this->memory}<br />";
    }
     
    public function getTime() 
    {  
        list($usec, $sec) = explode(" ", microtime());
        return ((float)$usec + (float)$sec);
    }
    public function getMemory()
    {
        return memory_get_usage();
    }
    public function convert($size)
    { 
        $unit=array(&#39;b&#39;,&#39;kb&#39;,&#39;mb&#39;,&#39;gb&#39;,&#39;tb&#39;,&#39;pb&#39;); 
        return @round($size/pow(1024,($i=floor(log($size,1024)))),2).&#39; &#39;.$unit[$i]; 
    } 
}

$a = array();
$b = new PerformanceTest();
$b->begin();
for($i=0;$i<500000;$i++){
$a[$i] = $i;
}
foreach($a as $i)
{
array_key_exists($i, $a);
}
$b->end();
/***
　　php 5.5n
　　time:0.131秒
　　memory:40.15 mb
　　php 7.0n
　　time:0.0780001秒
　　memory:14 mb
***/

$a = array();
$b = new PerformanceTest();
$b->begin();
for($i=0;$i<10000;$i++){
$a[$i] = $i;
}
foreach($a as $i)
{
in_array($i, $a);
}
$b->end();
/***
　　php 5.5n
　　time:0.6560001秒
　　memory:845.49 kb
　　php 7.0n
　　time:0.095秒
　　memory:388 kb
***/