php: Organize some useful custom functions

1. PHP encryption and decryption functions

PHP encryption and decryption functions can be used to encrypt some useful strings stored 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 random strings

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. PHP gets the file extension (suffix)

The following function can quickly get the file extension, that is, the 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 that is easy to read. , MB and other formats.

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: View the demo

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

5. PHP replacement tag characters

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 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 the directory For all files under, 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 method is as follows:

listDirFiles('home/some_folder/');

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