PHP generated 4 ways to share random numbers, arrays, 4 _php Tutorials

PHP generated 4 ways to share random numbers, arrays, 4 random numbers

Here are some ways to generate non-repeating random numbers, directly on the code bar

Copy the Code code as follows:
<?php
Define (' Random_max ', 100);
Define (' COUNT ', 10);

echo ' Max random num: '. Random_max, '; Result Count: '. COUNT, '
';

Invoke_entry (' Rand1 ');
Invoke_entry (' Rand2 ');
Invoke_entry (' Rand3 ');
Invoke_entry (' Rand4 ');

function Invoke_entry ($func _name) {
$time = new Time ();
$time->time_start ();
Call_user_func ($func _name);
echo $func _name ' time spend: ', $time->time_spend ();
Echo '
';
}
function Rand1 () {
$numbers = Range (1, Random_max);
Shuffle ($numbers); Randomly scrambled arrays
$result = Array_slice ($numbers, 1, COUNT);
return $result;
}
function Rand2 () {
$result = Array ();
while (count ($result) < count) {
$result [] = Mt_rand (1, Random_max); Mt_rand () is a better and faster random function than rand ()
$result = Array_unique ($result); Delete duplicate elements in an array
}
return $result;
}
function Rand3 () {
$result = Array ();
while (count ($result) < count) {
$_tmp = Mt_rand (1, Random_max);
if (!in_array ($_tmp, $result)) {//is allowed to be inserted when the same element does not exist in the array
$result [] = $_tmp;
}
}
return $result;
}
function Rand4 () {
$result = Array ();
while (count ($result) < count) {
$result [] = Mt_rand (1, Random_max);
$result = Array_flip (Array_flip ($result)); Array_flip to exchange the key and value of the array
}
return $result;
}
Class Time {
Private $_start;

Public Function Time_start () {
$this->_start = $this->microtime_float ();
}
Public Function Time_spend () {
return $this->microtime_float ()-$this->_start;
}
Private Function Microtime_float () {
List ($usec, $sec) = Explode ("", Microtime ());
return (float) $usec + (float) $sec);
}
}

?>

The fourth method is to turn over the method, using Array_flip () to flip the array's keys and values, using the PHP array feature, duplicate keys will overwrite, and then flip again, the same as the removal of duplicate values.
The above methods are simple examples, and some methods have limited scope of application.

Look at the efficiency of several methods:

With Array_unique () The performance is poor when the array is large, and of course shuffle () is affected by this.

http://www.bkjia.com/PHPjc/976033.html www.bkjia.com true http://www.bkjia.com/PHPjc/976033.html techarticle PHP generation of non-repeating random number, array of 4 ways to share, random number 4 below write several methods to generate non-repeating random numbers, directly on the Code bar copy code code as follows: PHP define ( ...

