Summary and arrangement of super practical php functions

1. PHP encryption and decryption

PHP encryption and decryption functions can be used to encrypt some useful strings and store them in the database, and reversibly decrypt the strings. This function uses base64 and MD5 encryption and decryption.

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; 
    } 
}

The usage method is as follows:

//以下是将字符串“Helloweba欢迎您”分别加密和解密 
//加密： 
echo encryptDecrypt('password', 'Helloweba欢迎您',0); 
//解密： 
echo encryptDecrypt('password', 'z0JAx4qMwcF+db5TNbp/xwdUM84snRsXvvpXuaCa4Bk=',1);

2. PHP generates a random string

When we need to generate a random name, temporary password and other strings, we can use the following function:

function generateRandomString($length = 10) { 
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; 
    $randomString = ''; 
    for ($i = 0; $i < $length; $i++) { 
        $randomString .= $characters[rand(0, strlen($characters) - 1)]; 
    } 
    return $randomString; 
}

The usage method is as follows:

echo generateRandomString(20);

3. Get the file extension (suffix) with PHP

The following function can quickly get the file extension or suffix.

function getExtension($filename){ 
  $myext = substr($filename, strrpos($filename, '.')); 
  return str_replace('.','',$myext); 
}

The usage method is as follows:

$filename = '我的文档.doc'; 
echo getExtension($filename);

4. PHP gets the file size and formats it

The function used below can get the file size and convert it into KB, MB and other formats that are easy to read.

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]);  
    } 
}

The usage method is as follows:

$thefile = filesize('test_file.mp3'); 
echo formatSize($thefile);

5. Replace tag characters in PHP

Sometimes we need to replace strings and template tags with specified content. You can use the following function:

function stringParser($string,$replacer){ 
    $result = str_replace(array_keys($replacer), array_values($replacer),$string); 
    return $result; 
}

The usage method is as follows:

$string = 'The {b}anchor text{/b} is the {b}actual word{/b} or words used {br}to describe the link {br}itself'; 
$replace_array = array(&#39;{b}&#39; => &#39;<b>&#39;,&#39;{/b}&#39; => &#39;</b>&#39;,&#39;{br}&#39; => &#39;<br />&#39;); 
echo stringParser($string,$replace_array);

6. PHP lists the file names in the directory

If you want to list all the files in the directory, use the following code:

function listDirFiles($DirPath){ 
    if($dir = opendir($DirPath)){ 
         while(($file = readdir($dir))!== false){ 
                if(!is_dir($DirPath.$file)) 
                { 
                    echo "filename: $file<br />"; 
                } 
         } 
    } 
}

The usage is as follows:

listDirFiles('home/some_folder/');

7. PHP gets the current page URL

The following function You can get the URL of the current page, whether it is http or https.

function curPageURL() { 
    $pageURL = 'http'; 
    if (!empty($_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; 
}

The usage method is as follows:

echo curPageURL();

8. Force download of files with PHP

Sometimes we don’t want the browser to directly open the file, such as PDF file, but to download the file directly, then the following function can force the download of the file, used in the function The application/octet-stream header type has been changed.

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!"; 
    } 
}

The usage method is as follows:

download('/down/test_45f73e852.zip');

9. PHP intercepts the length of a string

We often encounter situations where we need to intercept the length of a string (including Chinese characters). For example, the title cannot display more than a few characters. Use... means that the following functions can meet your needs.

/* 
 Utf-8、gb2312都支持的汉字截取函数 
 cut_str(字符串, 截取长度, 开始长度, 编码); 
 编码默认为 utf-8 
 开始长度默认为 0 
*/ 
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; 
    } 
}

The usage method is as follows:

$str = "jQuery插件实现的加载图片和页面效果"; 
echo cutStr($str,16);

10. Get the client’s real IP with PHP

We often use the database to record the user’s IP. The following code can get the client’s real IP:

//获取用户真实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); 
}

The usage method is as follows:

echo getIp();

11. PHP prevents SQL injection

When we query the database, for security reasons, we need to filter some illegal characters to prevent malicious SQL injection. Please take a look at the function:

function injCheck($sql_str) {  
    $check = preg_match('/select|insert|update|delete|\'|\/\*|\*|\.\.\/|\.\/|union|into|load_file|outfile/', $sql_str); 
    if ($check) { 
        echo '非法字符！！'; 
        exit; 
    } else { 
        return $sql_str; 
    } 
}

The usage method is as follows:

echo injCheck('1 or 1=1');

12. PHP page tips and Jump

When we perform form operations, sometimes we need to prompt the user for the operation results and jump to the relevant page for the sake of friendliness. Please see the following function:

function message($msgTitle,$message,$jumpUrl){ 
    $str = &#39;<!DOCTYPE HTML>&#39;; 
    $str .= &#39;<html>&#39;; 
    $str .= &#39;<head>&#39;; 
    $str .= &#39;<meta charset="utf-8">&#39;; 
    $str .= &#39;<title>页面提示</title>&#39;; 
    $str .= &#39;<style type="text/css">&#39;; 
    $str .= &#39;*{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}&#39;; 
    $str .= &#39;</style>&#39;; 
    $str .= &#39;</head>&#39;; 
    $str .= &#39;<body>&#39;; 
    $str .= &#39;<div>&#39;; 
    $str .= &#39;<h3 id="msgTitle">&#39;.$msgTitle.&#39;</h3>&#39;; 
    $str .= &#39;<div>&#39;; 
    $str .= &#39;<h4 id="message">&#39;.$message.&#39;</h4>&#39;; 
    $str .= &#39;<p>系统将在 <span style="color:blue;font-weight:bold">3</span> 秒后自动跳转,如果不想等待,直接点击 <a href="{$jumpUrl}">这里</a> 跳转</p>&#39;; 
    $str .= "<script>setTimeout(&#39;location.replace(\&#39;".$jumpUrl."\&#39;)&#39;,2000)</script>"; 
    $str .= &#39;</div>&#39;; 
    $str .= &#39;</div>&#39;; 
    $str .= &#39;</body>&#39;; 
    $str .= &#39;</html>&#39;; 
    echo $str; 
}

The usage method is as follows:

message('操作提示','操作成功！','http://www.helloweba.com/');

13. PHP calculation time

us When processing time, it is necessary to calculate the length of time from the current time to a certain point in time. For example, calculating the running time of the client is usually expressed by hh:mm:ss.

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; 
}

How to use is as follows:

$seconds = 3712; 
echo changeTimeType($seconds);