PHP 12个常用功能的函数

demo1.php

<?php
header('Content-Type: text/html; charset=utf-8');
//PHP加密解密
function encryptDecrypt($key, $string, $decrypt){
    if($decrypt){
        $decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($string), MCRYPT_MODE_CBC, md5(md5($key))), "12");
        return $decrypted;
    }else{
        $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $string, MCRYPT_MODE_CBC, md5(md5($key))));
        return $encrypted;
    }
}
//加密：
echo encryptDecrypt('demo', '网址：onestopweb.iteye.com',0),'<br>';
//解密：
echo encryptDecrypt('demo', 'lONfy9/i2RmCh31P/cKFfM6Jd90ijfg0rhJr1GihF+o=',1);

/* 输出效果：
 * lONfy9/i2RmCh31P/cKFfM6Jd90ijfg0rhJr1GihF+o=
 * 网址：onestopweb.iteye.com
 * */

demo2.php

<?php
//PHP生成随机字符串
function generateRandomString($length = 10) { 
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; 
    $randomString = ''; 
    for ($i = 0; $i < $length; $i++) { 
        $randomString .= $characters[rand(0, strlen($characters) - 1)]; 
    } 
    return $randomString; 
}
echo generateRandomString(20);

/* 输出效果：
 * 4e7ficXJk0jMvDQcCgZ8
 * */

demo3.php

<?php
//PHP获取文件扩展名（后缀）
function getExtension($filename){
    $myext = substr($filename, strrpos($filename, '.'));
    return str_replace('.','',$myext);
}
$filename = 'xxx.dd.gif';
echo getExtension($filename);

/* 输出效果：
 * gif
 * */

demo4.php

<?php
//PHP获取文件大小并格式化
function formatSize($size) {
    $sizes = array(" Bytes", " KB", " MB", " GB", " TB", " PB", " EB", " ZB", " YB");
    if ($size == 0) {
        return('n/a');
    } else {
        return (round($size/pow(1024, ($i = floor(log($size, 1024)))), 2) . $sizes[$i]);
    }
}
$thefile = filesize('demo.rar');
echo formatSize($thefile);

/* 输出效果：
 * 114.14 KB
 * */

demo5.php

<?php
header('Content-Type: text/html; charset=utf-8');
//PHP替换标签字符
function stringParser($string,$replacer){
    $result = str_replace(array_keys($replacer), array_values($replacer),$string);
    return $result;
}
$string = '阅谁问君诵，水落清香浮。';
$replace_array = array('阅' => '睇','君' => '你','浮' => '沉');

echo stringParser($string,$replace_array);

/* 输出效果：
 * 睇谁问你诵，水落清香沉。
 * */

demo6.php

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<?php
//PHP列出目录下的文件名
function listDirFiles($DirPath){
    if($dir = opendir($DirPath)){
        while(($file = readdir($dir))!== false){
            if(!is_dir($DirPath.$file))
            {
                echo "filename: $file<br />";
            }
        }
    }
}
listDirFiles('aaa');

/* 输出效果：
 * filename: bbb
 * filename: ccc
 * */

demo7.php

<?php
//PHP获取当前页面URL
//以下函数可以获取当前页面的URL，不管是http还是https。
function curPageURL() {
    $pageURL = 'http';
    if (!isset($_SERVER['HTTPS'])) {$pageURL .= "s";}
    $pageURL .= "://";
    if ($_SERVER["SERVER_PORT"] != "80") {
        $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
    } else {
        $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
    }
    return $pageURL;
}
echo curPageURL();

/* 输出效果：
 * http://192.168.0.180:84/demo7.php
 * */

demo8.php

<?php
//PHP强制下载文件
//有时我们不想让浏览器直接打开文件，如PDF文件，而是要直接下载文件
//那么以下函数可以强制下载文件，函数中使用了application/octet-stream头类型。
function download($filename){
    if ((isset($filename))&&(file_exists($filename))){
        header("Content-length: ".filesize($filename));
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename="' . $filename . '"');
        readfile("$filename");
    } else {
        echo "Looks like file does not exist!";
    }
}
download('demo.rar');

/* 输出效果：
 * 直接下载指定的文件
 * */

demo9.php

<?php
header('Content-Type: text/html; charset=utf-8');
//PHP截取字符串长度
//超过多少字符，超出的长度用…表示
function cutStr($string, $sublen, $start = 0, $code = 'UTF-8'){
    if($code == 'UTF-8'){
        $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";
        preg_match_all($pa, $string, $t_string);

        if(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."...";
        return join('', array_slice($t_string[0], $start, $sublen));
    }else{
        $start = $start*2;
        $sublen = $sublen*2;
        $strlen = strlen($string);
        $tmpstr = '';

        for($i=0; $i<$strlen; $i++){
            if($i>=$start && $i<($start+$sublen)){
                if(ord(substr($string, $i, 1))>129){
                    $tmpstr.= substr($string, $i, 2);
                }else{
                    $tmpstr.= substr($string, $i, 1);
                }
            }
            if(ord(substr($string, $i, 1))>129) $i++;
        }
        if(strlen($tmpstr)<$strlen ) $tmpstr.= "...";
        return $tmpstr;
    }
}
$str = "阅谁问君诵，水落清香浮。";
echo cutStr($str,10);

/* 输出效果：
 * 阅谁问君诵，水落清香...
 * */

demo10.php

<?php
//PHP获取客户端真实IP
function getIp() {
    if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
        $ip = getenv("HTTP_CLIENT_IP");
        else
            if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
                $ip = getenv("HTTP_X_FORWARDED_FOR");
                else
                    if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
                        $ip = getenv("REMOTE_ADDR");
                        else
                            if (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
                                $ip = $_SERVER['REMOTE_ADDR'];
                                else
                                    $ip = "unknown";
                                    return ($ip);
}
echo getIp();

/* 输出效果：
 * 192.168.0.180
 * */

demo11.php

<?php
header('Content-Type: text/html; charset=utf-8');
//PHP页面提示与跳转
function message($msgTitle,$message,$jumpUrl){ 
    $str = '<!DOCTYPE HTML>'; 
    $str .= '<html>'; 
    $str .= '<head>'; 
    $str .= '<meta charset="utf-8">'; 
    $str .= '<title>页面提示</title>'; 
    $str .= '<style type="text/css">'; 
    $str .= '*{margin:0; padding:0}a{color:#369; text-decoration:none;}a:hover{text-decoration:underline}body{height:100%; font:12px/18px Tahoma, Arial,  sans-serif; color:#424242; background:#fff}.message{width:450px; height:120px; margin:16% auto; border:1px solid #99b1c4; background:#ecf7fb}.message h3{height:28px; line-height:28px; background:#2c91c6; text-align:center; color:#fff; font-size:14px}.msg_txt{padding:10px; margin-top:8px}.msg_txt h4{line-height:26px; font-size:14px}.msg_txt h4.red{color:#f30}.msg_txt p{line-height:22px}'; 
    $str .= '</style>'; 
    $str .= '</head>'; 
    $str .= '<body>'; 
    $str .= '<div>'; 
    $str .= '<h3>'.$msgTitle.'</h3>'; 
    $str .= '<div>'; 
    $str .= '<h4>'.$message.'</h4>'; 
    $str .= '<p>系统将在 <span style="color:blue;font-weight:bold">3</span> 秒后自动跳转,如果不想等待,直接点击 <a href="{$jumpUrl}">这里</a> 跳转</p>'; 
    $str .= "<script>setTimeout('location.replace(\'".$jumpUrl."\')',2000)</script>"; 
    $str .= '</div>'; 
    $str .= '</div>'; 
    $str .= '</body>'; 
    $str .= '</html>'; 
    echo $str; 
}
message('操作提示','操作成功！','http://onestopweb.iteye.com/');

/* 输出效果：
 * 操作提示
 * 操作成功！
 * 系统将在 3 秒后自动跳转,如果不想等待,直接点击 这里 跳转
 * */

demo12.php

<?php
//PHP计算时长
function changeTimeType($seconds) {
    if ($seconds > 3600) {
        $hours = intval($seconds / 3600);
        $minutes = $seconds % 3600;
        $time = $hours . ":" . gmstrftime('%M:%S', $minutes);
    } else {
        $time = gmstrftime('%H:%M:%S', $seconds);
    }
    return $time;
}
$seconds = 23;
echo changeTimeType($seconds);

/* 输出效果：
 * 00:00:23
 * */