使用PHP開發應用程序，尤其是網站程序，常常需要產生隨機密碼，如用戶註冊生成隨機密碼，用戶重置密碼也需要產生一個隨機的密碼。隨機密碼也就是一串固定長度的字串，這裡我收集整理了幾種產生隨機字串的方法，以供大家參考。
方法一：
1、在33 – 126 中產生一個隨機整數，如35，
2、將35 轉換成對應的ASCII碼字符，如35 對應
2、將35 轉換成對應的ASCII碼字符，如35 對應331 、2 步驟n 次，連接成n 位的密碼該演算法主要用到了兩個函數，mt_rand ( int $min , int $max )函數用於產生隨機整數，其中$min – $max 為ASCII 碼的範圍，這裡取33 -126 ，可以根據需要調整範圍，如ASCII碼表中97 – 122 位元對應a – z 的英文字母，具體可參考ASCII碼表； chr ( int $ascii )函數用於將對應整數$ascii 轉換成對應的字元。 view sourceprint?
<ol>
<li><span><span>function</span><span> create_password(</span><span>$pw_length</span><span> = 8) </span></span></li>
<li><span>{ </span></li>
<li><span> <span>$randpwd</span><span> = </span><span>''</span><span>; </span></span></li>
<li><span> <span>for</span><span> (</span><span>$i</span><span> = 0; </span><span>$i</span><span> < </span><span>$pw_length</span><span>; </span><span>$i</span><span>++) </span></span></li><li><span> { </span></li><li><span> <span>$randpwd</span><span> .= </span><span>chr</span><span>(mt_rand(33, 126)); </span></span></li><li><span> } </span></li><li><span> <span>return</span><span> </span><span>$randpwd</span><span>; </span></span></li><li><span>} </span></li><li><span> </span></li><li><span><span>// 调用该函数，传递长度参数$pw_length = 6</span><span> </span></span></li><li><span><span>echo</span><span> create_password(6); </span></span></li></ol>view sourceprint?
<ol><li><span><span>function</span><span> generate_password( </span><span>$length</span><span> = 8 ) { </span></span></li><li><span> <span>// 密码字符集，可任意添加你需要的字符</span><span> </span></span></li><li><span> <span>$chars</span><span> = </span><span>'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/?|'</span><span>; </span></span></li>
<li><span> </span></li>
<li><span> <span>$password</span><span> = </span><span>''</span><span>; </span></span></li>
<li><span> <span>for</span><span> ( </span><span>$i</span><span> = 0; </span><span>$i</span><span> < </span><span>$length</span><span>; </span><span>$i</span><span>++ ) </span></span></li><li><span> { </span></li><li><span> <span>// 这里提供两种字符获取方式</span><span> </span></span></li><li><span> <span>// 第一种是使用 substr 截取$chars中的任意一位字符；</span><span> </span></span></li><li><span> <span>// 第二种是取字符数组 $chars 的任意元素</span><span> </span></span></li><li><span> <span>// $password .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);</span><span> </span></span></li><li><span> <span>$password</span><span> .= </span><span>$chars</span><span>[ mt_rand(0, </span><span>strlen</span><span>(</span><span>$chars</span><span>) - 1) ]; </span></span></li><li><span> } </span></li><li><span> </span></li><li><span> <span>return</span><span> </span><span>$password</span><span>; </span></span></li><li><span>} </span></li></ol><ol><li><span><span>function</span><span> make_password( </span><span>$length</span><span> = 8 ) </span></span></li><li><span>{ </span></li><li><span> <span>// 密码字符集，可任意添加你需要的字符</span><span> </span></span></li><li><span> <span>$chars</span><span> = </span><span>array</span><span>(</span><span>'a'</span><span>, </span><span>'b'</span><span>, </span><span>'c'</span><span>, </span><span>'d'</span><span>, </span><span>'e'</span><span>, </span><span>'f'</span><span>, </span><span>'g'</span><span>, </span><span>'h'</span><span>, </span></span></li><li><span> <span>'i'</span><span>, </span><span>'j'</span><span>, </span><span>'k'</span><span>, </span><span>'l'</span><span>,</span><span>'m'</span><span>, </span><span>'n'</span><span>, </span><span>'o'</span><span>, </span><span>'p'</span><span>, </span><span>'q'</span><span>, </span><span>'r'</span><span>, </span><span>'s'</span><span>, </span></span></li><li><span> <span>'t'</span><span>, </span><span>'u'</span><span>, </span><span>'v'</span><span>, </span><span>'w'</span><span>, </span><span>'x'</span><span>, </span><span>'y'</span><span>,</span><span>'z'</span><span>, </span><span>'A'</span><span>, </span><span>'B'</span><span>, </span><span>'C'</span><span>, </span><span>'D'</span><span>, </span></span></li><li><span> <span>'E'</span><span>, </span><span>'F'</span><span>, </span><span>'G'</span><span>, </span><span>'H'</span><span>, </span><span>'I'</span><span>, </span><span>'J'</span><span>, </span><span>'K'</span><span>, </span><span>'L'</span><span>,</span><span>'M'</span><span>, </span><span>'N'</span><span>, </span><span>'O'</span><span>, </span></span></li><li><span> <span>'P'</span><span>, </span><span>'Q'</span><span>, </span><span>'R'</span><span>, </span><span>'S'</span><span>, </span><span>'T'</span><span>, </span><span>'U'</span><span>, </span><span>'V'</span><span>, </span><span>'W'</span><span>, </span><span>'X'</span><span>, </span><span>'Y'</span><span>,</span><span>'Z'</span><span>, </span></span></li><li><span> <span>'0'</span><span>, </span><span>'1'</span><span>, </span><span>'2'</span><span>, </span><span>'3'</span><span>, </span><span>'4'</span><span>, </span><span>'5'</span><span>, </span><span>'6'</span><span>, </span><span>'7'</span><span>, </span><span>'8'</span><span>, </span><span>'9'</span><span>, </span><span>'!'</span><span>, </span></span></li><li><span> <span>'@'</span><span>,</span><span>'#'</span><span>, </span><span>'$'</span><span>, </span><span>'%'</span><span>, </span><span>'^'</span><span>, </span><span>'&'</span><span>, </span><span>'*'</span><span>, </span><span>'('</span><span>, </span><span>')'</span><span>, </span><span>'-'</span><span>, </span><span>'_'</span><span>, </span></span></li><li><span> <span>'['</span><span>, </span><span>']'</span><span>, </span><span>'{'</span><span>, </span><span>'}'</span><span>, </span><span>'<'</span><span>, </span><span>'>'</span><span>, </span><span>'~'</span><span>, </span><span>'`'</span><span>, </span><span>'+'</span><span>, </span><span>'='</span><span>, </span><span>','</span><span>, </span></span></li>
<li><span> <span>'.'</span><span>, </span><span>';'</span><span>, </span><span>':'</span><span>, </span><span>'/'</span><span>, </span><span>'?'</span><span>, </span><span>'|'</span><span>); </span></span></li>
<li><span> </span></li>
<li><span> <span>// 在 $chars 中随机取 $length 个数组元素键名</span><span> </span></span></li>
<li><span> <span>$keys</span><span> = </span><span>array_rand</span><span>(</span><span>$chars</span><span>, </span><span>$length</span><span>); </span></span></li>
<li><span> </span></li>
<li><span> <span>$password</span><span> = </span><span>''</span><span>; </span></span></li>
<li><span> <span>for</span><span>(</span><span>$i</span><span> = 0; </span><span>$i</span><span> < </span><span>$length</span><span>; </span><span>$i</span><span>++) </span></span></li><li><span> { </span></li><li><span> <span>// 将 $length 个数组元素连接成字符串</span><span> </span></span></li><li><span> <span>$password</span><span> .= </span><span>$chars</span><span>[</span><span>$keys</span><span>[</span><span>$i</span><span>]]; </span></span></li><li><span> } </span></li><li><span> </span></li><li><span> <span>return</span><span> </span><span>$password</span><span>; </span></span></li><li><span>} </span></li></ol>方法四：
本方法是本文被藍色理想轉載後，一位網友提供的一個新方法，簡單，本方法是本文被藍色理想轉載後，一位網友提供的一個新方法，只是簡單，紙，只是因為簡單(md)函數的回傳值的緣故，產生的密碼只包括字母和數字，不過也算是不錯的方法。演算法思想：
1、time() 取得目前的Unix 時間戳
2、將第一步取得的時間戳進行md5() 加密
3、將第二步加密的結果，截取n 位元即得想要的密碼
view sourceprint?
<ol><li><span><span>function</span><span> get_password( </span><span>$length</span><span> = 8 ) </span></span></li><li><span>{ </span></li><li><span> <span>$str</span><span> = </span><span>substr</span><span>(md5(time()), 0, 6); </span></span></li><li><span> <span>return</span><span> </span><span>$str</span><span>; </span></span></li><li><span>} </span></li></ol>我們使用以下PHP程式碼，計算上面的4 個隨機密碼產生6 位密碼的運行時間，進6 位密碼的運行時間，而對他們的4 個隨機密碼產生6 位密碼的運行時間，進6 位元密碼的運行時間，而對他們的4 個隨機密碼生成時間效率進行一個簡單的比較。
view sourceprint?
<ol><li><span><span><?php </span></span></li><li><span><span>function</span><span> getmicrotime() </span></span></li><li><span>{ </span></li><li><span> list(<span>$usec</span><span>, </span><span>$sec</span><span>) = </span><span>explode</span><span>(</span><span>" "</span><span>,microtime()); </span></span></li><li><span> <span>return</span><span> ((float)</span><span>$usec</span><span> + (float)</span><span>$sec</span><span>); </span></span></li><li><span>} </span></li><li><span> </span></li><li><span><span>// 记录开始时间</span><span> </span></span></li><li><span><span>$time_start</span><span> = getmicrotime(); </span></span></li><li><span> </span></li><li><span><span>// 这里放要执行的PHP代码，如:</span><span> </span></span></li><li><span><span>// echo create_password(6);</span><span> </span></span></li><li><span> </span></li><li><span><span>// 记录结束时间</span><span> </span></span></li><li><span><span>$time_end</span><span> = getmicrotime(); </span></span></li><li><span><span>$time</span><span> = </span><span>$time_end</span><span> - </span><span>$time_start</span><span>; </span></span></li><li><span> </span></li><li><span> <span>// 输出运行总时间 </span><span> </span></span></li><li><span><span>echo</span><span> </span><span>"执行时间 $time seconds"</span><span>; </span></span></li><li><span>?> </span></span></li>
</ol>方法一：9.8943710327148E-5575357575753253535方法三：0.00017499923706055 秒
方法四：3.4093856811523E-5 秒
可以看出方法一和方法二的執行時間都差不多，方法四運行時間最短，而方法三的運行時間稍微長點。
以上就介紹了PHP產生隨機密碼的4種方法及效能對比，包括了方面的內容，希望對PHP教程有興趣的朋友有所幫助。
