In PHP, the mt_rand() and rand() functions can randomly generate a pure number. They both require me to set the seed data and then generate it. So which one of mt_rand() and rand() has better performance? Below I will When in doubt, test it out.
Example 1. mt_rand() example
| The code is as follows |
Copy code |
| 代码如下 |
复制代码 |
|
echo mt_rand() . "n";
echo mt_rand() . "n";
echo mt_rand(5, 15);
?>
上例的输出类似于：
1604716014
1478613278
6
|
echo mt_rand() . "n";
echo mt_rand() . "n";
echo mt_rand(5, 15);
?>
The output of the above example is similar to:
1604716014
1478613278
6
|
Note: As of PHP 4.2.0, it is no longer necessary to seed the random number generator with the srand() or mt_srand() function, it is now done automatically.
Note: In versions before 3.0.7, max means range. To get the same random numbers from 5 to 15 as in the above example in these versions, the short example is mt_rand (5, 11).
See mt_srand(), mt_getrandmax() and rand().
The rand() function returns a random integer.
Grammar
rand(min,max) parameter description
min,max are optional. Specifies the range of random number generation.
Description
If the optional parameters min and max are not provided, rand() returns a pseudo-random integer between 0 and RAND_MAX. For example, if you want a random number between 5 and 15 (inclusive), use rand(5, 15).
Tips and Notes
Note: On some platforms (e.g. Windows) RAND_MAX is only 32768. If you need a range greater than 32768, specify the min and max parameters to generate a number greater than RAND_MAX, or consider using mt_rand() instead.
Note: As of PHP 4.2.0, seeding the random number generator with the srand() or mt_srand() functions is no longer necessary, it is now done automatically.
| 代码如下 |
复制代码 |
|
$max = 100000;
$timeparts = explode(' ',microtime());
$stime = $timeparts[1].substr($timeparts[0],1);
$i = 0;
while($i < $max) {
rand();
$i++;
}
$timeparts = explode(' ',microtime());
$etime = $timeparts[1].substr($timeparts[0],1);
$time = $etime-$stime;
echo "{$max} random numbers generated in {$time} seconds using rand();
";
$timeparts = explode(' ',microtime());
$stime = $timeparts[1].substr($timeparts[0],1);
$i = 0;
while($i < $max) {
mt_rand();
$i++;
}
$timeparts = explode(' ',microtime());
$etime = $timeparts[1].substr($timeparts[0],1);
$time = $etime-$stime;
echo "{$max} random numbers generated in {$time} seconds using mt_rand();
";
?>
|
Note: In versions before 3.0.7, max means range. To get the same random numbers from 5 to 15 as in the above example in these versions, the short example is rand (5, 11).
Is mt_rand() really 4 times faster than rand()?
With this question in mind, I tested it myself while reading the introduction on the Internet. The test is as follows.
Comparison test 1 between mt_rand() and rand()
Test code:
| The code is as follows |
Copy code |
|
$max = 100000;
$timeparts = explode(' ',microtime());
$stime = $timeparts[1].substr($timeparts[0],1);
$i = 0;
while($i < $max) {<🎜>
rand();<🎜>
$i++;<🎜>
}<🎜>
$timeparts = explode(' ',microtime());<🎜>
$etime = $timeparts[1].substr($timeparts[0],1);<🎜>
$time = $etime-$stime;<🎜>
echo "{$max} random numbers generated in {$time} seconds using rand();<🎜>
";<🎜>
<🎜>$timeparts = explode(' ',microtime());<🎜>
$stime = $timeparts[1].substr($timeparts[0],1);<🎜>
$i = 0;<🎜>
while($i < $max) {<🎜>
mt_rand();<🎜>
$i++;<🎜>
}<🎜>
$timeparts = explode(' ',microtime());<🎜>
$etime = $timeparts[1].substr($timeparts[0],1);<🎜>
$time = $etime-$stime;<🎜>
echo "{$max} random numbers generated in {$time} seconds using mt_rand();<🎜>
";<🎜>
?>
|
Result:
First test
100000 random numbers generated in 0.024894952774048 seconds using rand();
100000 random numbers generated in 0.028925895690918 seconds using mt_rand();
Second test
100000 random numbers generated in 0.03147292137146 seconds using rand();
100000 random numbers generated in 0.02997088432312 seconds using mt_rand();
The third test
100000 random numbers generated in 0.028102874755859 seconds using rand();
100000 random numbers generated in 0.02803111076355 seconds using mt_rand();
The fourth test
100000 random numbers generated in 0.025573015213013 seconds using rand();
100000 random numbers generated in 0.028030157089233 seconds using mt_rand();
This result is only displayed several times. If you test it a few times, you will find that the two changes alternately. In fact, there is not much difference between the two.
Comparison test 2 between mt_rand() and rand()
My own testing environment
Operating system: windows xp
apache 2.0
php 5.2.12
Memory 2G
| The code is as follows |
Copy code |
| 代码如下 |
复制代码 |
|
function microtime_float()
{
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
$time_start = microtime_float();
for($i=0; $i<1000000; ++$i)
{
rand();
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "rand() cost $time secondsn";
$time_start = microtime_float();
for($i=0; $i<1000000; ++$i)
{
mt_rand();
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "mt_rand() cost $time secondsn";
?>
|
function microtime_float()
{
List($usec, $sec) = explode(" ", microtime());
Return ((float)$usec + (float)$sec);
}
$time_start = microtime_float();
for($i=0; $i<1000000; ++$i)
{
rand();
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "rand() cost $time secondsn";
$time_start = microtime_float();
for($i=0; $i<1000000; ++$i)
{
mt_rand();
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "mt_rand() cost $time secondsn";
?>
|
Result:
First time
rand() cost 0.25919604301453 seconds
mt_rand() cost 0.28554391860962 seconds
Second time
rand() cost 0.31136202812195 seconds
mt_rand() cost 0.28973197937012 seconds
The third time
rand() cost 0.27545690536499 seconds
mt_rand() cost 0.27108001708984 seconds
The fourth time
rand() cost 0.26263308525085 seconds
mt_rand() cost 0.27727103233337 seconds
The result is still the same: the time taken by the two changes alternately, but in fact there is not much difference between the two
Comparison conclusion between php’s mt_rand() and rand()
I have read many other people’s tests online, both in Linux and Windows environments. Most people’s results are the same as mine: there is almost no difference between the two, but some people have measured that mt_rand() is better than rand() It is 4 times faster, but since they did not give a specific test environment, they cannot judge whether it is true or false. I still believe in my conclusion because I saw someone introducing mt_rand() and rand() like this:
So why does the PHP manual say that mt_rand() is 4 times faster than rand()?
Since 2004, rand() has started using algorithmthm, so now there is not much difference in speed
From the various tests above, there is no difference between them, but the values may change in different systems.
http://www.bkjia.com/PHPjc/445615.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445615.htmlTechArticleIn php, the mt_rand() and rand() functions can randomly generate a pure number. They are I need to set up the seed data and then generate it, then the performance of mt_rand() and rand() will be better...
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
