Web开发者必备：21个超实用PHP代码

1. PHP可阅读随机字符串

此代码将创建一个可阅读的字符串，使其更接近词典中的单词，实用且具有密码验证功能。

/***************
@length - length of random string (must be a multiple of 2)**************/
function readable_random_string($length = 6){
 $conso=array("b","c","d","f","g","h","j","k","l",
 "m","n","p","r","s","t","v","w","x","y","z");
$vocal=array("a","e","i","o","u");
$password="";
srand ((double)microtime()*1000000);
$max = $length/2;
for($i=1;
$i<=$max; $i++)
{
$password.=$conso[rand(0,19)];
$password.=$vocal[rand(0,4)];
}
return $password;
}

   2. PHP生成一个随机字符串

如果不需要可阅读的字符串，使用此函数替代，即可创建一个随机字符串，作为用户的随机密码等。

/*************
*@l - length of random string
*/
function generate_rand($l){
$c= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
srand((double)microtime()*1000000);
for($i=0; $i<$l; $i++) {
$rand.= $c[rand()%strlen($c)];
}
return $rand;
 }

   3. PHP编码电子邮件地址

使用此代码，可以将任何电子邮件地址编码为 html 字符实体，以防止被垃圾邮件程序收集。

function encode_email($email='[email protected]', $linkText='Contact Us', $attrs ='class="emailencoder"' )
{
// remplazar aroba y puntos
$email = str_replace('@', '@', $email);
$email = str_replace('.', '.', $email);
$email = str_split($email, 5);
$linkText = str_replace('@', '@', $linkText);
$linkText = str_replace('.', '.', $linkText);
$linkText = str_split($linkText, 5); $part1 = 'part2 = 'ilto:'; $part3 = '" '. $attrs .' >';
$part4 = '';
$encoded = '';
$encoded .= "document.write('$part1');";
$encoded .= "document.write('$part2');";
foreach($email as $e)
{
$encoded .= "document.write('$e');";
 }
$encoded .= "document.write('$part3');";
 foreach($linkText as $l)
{
 $encoded .= "document.write('$l');";
}
$encoded .= "document.write('$part4');";
$encoded .= ''; return $encoded;}

4. PHP验证邮件地址

电子邮件验证也许是中最常用的网页表单验证，此代码除了验证电子邮件地址，也可以选择检查邮件域所属 DNS 中的 MX 记录，使邮件验证功能更加强大。

function is_valid_email($email, $test_mx = false)
{
 if(eregi("^([_a-z0-9-]+)(\.[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$", $email)) if($test_mx)
 {
list($username, $domain) = split("@", $email);
return getmxrr($domain, $mxrecords);
}
else
return true;
else
return false;
}   5. PHP列出目录内容function list_files($dir){
 if(is_dir($dir))
 {
if($handle = opendir($dir)) {
 while(($file = readdir($handle)) !== false)
{
if($file != "." && $file != ".." && $file != "Thumbs.db")
 { echo '<a target="_blank" href="'.$dir.$file.'">'.$file.'a><br>'."\n";
}
}
 closedir($handle);
}
}
}  6. PHP销毁目录删除一个目录，包括它的内容。/*****
*@dir - Directory to destroy
*@virtual[optional]- whether a virtual directory
*/
function destroyDir($dir, $virtual = false)
{
$ds = DIRECTORY_SEPARATOR;
$dir = $virtual ? realpath($dir) : $dir;
$dir = substr($dir, -1) == $ds ? substr($dir, 0, -1) : $dir;
if (is_dir($dir) && $handle = opendir($dir))
 {
 while ($file = readdir($handle))
{
if ($file == '.' || $file == '..')
{
 continue;
 }
elseif (is_dir($dir.$ds.$file))
{
destroyDir($dir.$ds.$file);
 }
else
{
 unlink($dir.$ds.$file);
}
 }
closedir($handle);
 rmdir($dir);
return true;
}
else
 {
return false;
 }
}   7. PHP解析 JSON 数据与大多数流行的 Web 服务如 twitter 通过开放 API 来提供数据一样，它总是能够知道如何解析 API 数据的各种传送格式，包括 JSON，XML 等等。$json_string='{"id":1,"name":"foo","email":"[email protected]","interest":["wordpress","php"]} ';
$obj=json_decode($json_string);
echo $obj->name; //prints foo
echo $obj->interest[1]; //prints php8. PHP解析 XML 数据//xml string
$xml_string="xml version='1.0'?>
<users>
 <user id='398'>
 <name>Fooname>
<email>[email protected]name>
 user>
<user id='867'>
 <name>Foobarname>
<email>[email protected]name>
user>users>";
 //load the xml string using simplexml
$xml = simplexml_load_string($xml_string);
 //loop through the each node of user
foreach ($xml->user as $user)
{
//access attribute
 echo $user['id'], ' ';
//subnodes are accessed by -> operator
echo $user->name, ' ';
echo $user->email, '<br />';
}9. PHP创建日志缩略名创建用户友好的日志缩略名。function create_slug($string){
$slug=preg_replace('/[^A-Za-z0-9-]+/', '-', $string);
 return $slug;
}  10. PHP获取客户端真实 IP 地址 该函数将获取用户的真实 IP 地址，即便他使用代理服务器。function getRealIpAddr()
{
if (!emptyempty($_SERVER['HTTP_CLIENT_IP']))
{
$ip=$_SERVER['HTTP_CLIENT_IP'];
}
 elseif (!emptyempty($_SERVER['HTTP_X_FORWARDED_FOR']))
//to check ip is pass from proxy
{
$ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
}
else
 {
$ip=$_SERVER['REMOTE_ADDR'];
}
return $ip;
}11. PHP强制性文件下载为用户提供强制性的文件下载功能。/********************
*@file - path to file
*/
function force_download($file)
{
if ((isset($file))&&(file_exists($file))) {
header("Content-length: ".filesize($file));
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="' . $file . '"');
readfile("$file");
}
else {
 echo "No file selected";
 }
}  12. PHP创建标签云function getCloud( $data = array(), $minFontSize = 12, $maxFontSize = 30 )
{
$minminimumCount = min( array_values( $data ) );
$maxmaximumCount = max( array_values( $data ) );
$spread = $maximumCount - $minimumCount; $cloudHTML = '';
$cloudTags = array();
$spread == 0 && $spread = 1;
foreach( $data as $tag => $count )
 {
$size = $minFontSize + ( $count - $minimumCount ) * ( $maxFontSize - $minFontSize ) / $spread;
 $cloudTags[] = '<a style="font-size: ' . floor( $size ) . 'px'
 . '" href="#" title="\'' . $tag .
 '\' returned a count of ' . $count . '">'
 . htmlspecialchars( stripslashes( $tag ) ) . 'a>';
 }
return join( "\n", $cloudTags ) . "\n";
}
/***************************
*** Sample usage ***/
$arr = Array('Actionscript' => 35, 'Adobe' => 22, 'Array' => 44, 'Background' => 43,
'Blur' => 18, 'Canvas' => 33, 'Class' => 15, 'Color Palette' => 11, 'Crop' => 42,
'Delimiter' => 13, 'Depth' => 34, 'Design' => 8, 'Encode' => 12, 'Encryption' => 30,
'Extract' => 28, 'Filters' => 42);
echo getCloud($arr, 12, 36);
 13. PHP寻找两个字符串的相似性PHP 提供了一个极少使用的 similar_text 函数，但此函数非常有用，用于比较两个字符串并返回相似程度的百分比。similar_text($string1, $string2, $percent);
//$percent will have the percentage of similarity14. PHP在应用程序中使用 Gravatar 通用头像随着 WordPress 越来越普及，Gravatar 也随之流行。由于 Gravatar 提供了易于使用的 API，将其纳入应用程序也变得十分方便。/******************
*@email - Email address to show gravatar for
*@size - size of gravatar
*@default - URL of default gravatar to use
*@rating - rating of Gravatar(G, PG, R, X)
*/
function show_gravatar($email, $size, $default, $rating)
{
 echo '<img src="http://www.gravatar.com/avatar.php?gravatar_id='.md5($email).
 '&default='.$default.'&size='.$size.'&rating='.$rating.'" width="'.$size.'px"
height="'.$size.'px" />';
}
  15. PHP在字符断点处截断文字所谓断字 (word break)，即一个单词可在转行时断开的地方。这一函数将在断字处截断字符串。// Original PHP code by Chirp Internet: www.chirp.com.au
// Please acknowledge use of this code by including this header.
function myTruncate($string, $limit, $break=".", $pad="...") {
// return with no change if string is shorter than $limit
if(strlen($string) <= $limit)
 return $string;
// is $break present between $limit and the end of the string?
if(false !== ($breakpoint = strpos($string, $break, $limit))) {
 if($breakpoint < strlen($string) - 1) {
$string = substr($string, 0, $breakpoint) . $pad;
 }
 }
 return $string;
}
/***** Example ****/
$short_string=myTruncate($long_string, 100, ' '); 16. PHP文件 Zip 压缩/* creates a compressed zip file */
function create_zip($files = array(),$destination = '',$overwrite = false) {
//if the zip file already exists and overwrite is false, return false
 if(file_exists($destination) && !$overwrite) { return false; }
//vars $valid_files = array();
//if files were passed in...
if(is_array($files)) {
//cycle through each file
foreach($files as $file) {
 //make sure the file exists
 if(file_exists($file)) {
$valid_files[] = $file;
 }
}
}
//if we have good files...
if(count($valid_files)) {
 //create the archive
$zip = new ZipArchive();
if($zip->open($destination,$overwrite ? ZIPARCHIVE::OVERWRITE : ZIPARCHIVE::CREATE) !== true) { return false;
 }
//add the files
foreach($valid_files as $file) {
$zip->addFile($file,$file);
 }
//debug //echo 'The zip archive contains ',$zip->numFiles,' files with a status of ',$zip->status;
//close the zip -- done!
 $zip->close();
//check to make sure the file exists
 return file_exists($destination);
 }
else
{
 return false;
}
}
/***** Example Usage ***/
$files=array('file1.jpg', 'file2.jpg', 'file3.gif');
create_zip($files, 'myzipfile.zip', true);17. PHP解压缩 Zip 文件/**********************
*@file - path to zip file
*@destination - destination directory for unzipped files
*/
function unzip_file($file, $destination){
// create object
$zip = new ZipArchive() ;
// open archive
if ($zip->open($file) !== TRUE) {
die (’Could not open archive’);
}
// extract contents to destination directory
$zip->extractTo($destination);
// close archive
$zip->close();
echo 'Archive extracted to directory';
}
 18. PHP为 URL 地址预设 http 字符串有时需要接受一些表单中的网址输入，但用户很少添加 http:// 字段，此代码将为网址添加该字段。if (!preg_match("/^(http|ftp):/", $_POST['url'])) {
$_POST['url'] = 'http://'.$_POST['url'];
}
 19. PHP将网址字符串转换成超级链接该函数将 URL 和 E-mail 地址字符串转换为可点击的超级链接。function makeClickableLinks($text) {
$text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&//=]+)',
'<a href="\1">\1a>', $text);
$text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)',
'\1<a href="http://\2">\2a>', $text);
$text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',
'<a href="mailto:\1">\1a>', $text);

return $text;
} 20. PHP调整图像尺寸创建图像缩略图需要许多时间，此代码将有助于了解缩略图的逻辑。/**********************
*@filename - path to the image
*@tmpname - temporary path to thumbnail
*@xmax - max width
*@ymax - max height
*/
function resize_image($filename, $tmpname, $xmax, $ymax)
{
$ext = explode(".", $filename);
$ext = $ext[count($ext)-1];

if($ext == "jpg" || $ext == "jpeg")
$im = imagecreatefromjpeg($tmpname);
elseif($ext == "png")
$im = imagecreatefrompng($tmpname);
elseif($ext == "gif")
$im = imagecreatefromgif($tmpname);

$x = imagesx($im);
$y = imagesy($im);

if($x <= $xmax && $y <= $ymax)
return $im;

if($x >= $y) {
$newx = $xmax;
$newy = $newx * $y / $x;
}
else {
$newy = $ymax;
$newx = $x / $y * $newy;
}

$im2 = imagecreatetruecolor($newx, $newy);
imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);
return $im2;
}   21. PHP检测 ajax 请求大多数的 JavaScript 框架如 jquery，Mootools 等，在发出 Ajax 请求时，都会发送额外的 HTTP_X_REQUESTED_WITH 头部信息，头当他们一个ajax请求，因此你可以在服务器端侦测到 Ajax 请求。if(!emptyempty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){
//If AJAX Request Then
}else{
//something else
}