php生成不重复随机数、数组的4种方法分享

echo 'max random num: '.RANDOM_MAX,' ;result count:'.COUNT,'<br/>';PHP教程

invoke_entry('rand1');
invoke_entry('rand2');
invoke_entry('rand3');
invoke_entry('rand4');PHP教程

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 '<br/>';
}
function rand1() {
?$numbers = range (1,RANDOM_MAX);
?shuffle($numbers);?//随机打乱数组
?$result = array_slice($numbers,1,COUNT);
?return $result;
}
function rand2() {
?$result = array();
?while(count($result)< COUNT) {
??$result[] = mt_rand(1,RANDOM_MAX);?//mt_rand()是比rand()更好更快的随机函数
??$result = array_unique($result); //删除数组中重复的元素
?}
?return $result;
}
function rand3() {
?$result = array();??
?while(count($result) < COUNT) {
??$_tmp = mt_rand(1,RANDOM_MAX);
??if(!in_array($_tmp,$result)) {?//当数组中不存在相同的元素时,才允许插入
???$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将数组的key和value交换
?}
?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);
?}
}PHP教程

?>
PHP教程