PHP 实用代码收集

1. 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. 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. 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='[e-mail]', $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 = '<a href="ma';
$part2 = 'ilto:';
$part3 = '" '. $attrs .' >';
$part4 = '</a>';

$encoded = '<script type="text/javascript">';
$encoded .= "document.write('$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 .= '</script>';

return $encoded;
}

4. 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. 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. 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. 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":"[e-mail]","interest":["wordpress","php"]} ';
$obj=json_decode($json_string);
echo $obj->name; //prints foo
echo $obj->interest[1]; //prints php

8. 解析 xml 数据

//xml string
$xml_string="<?xml version='1.0'?>
<users>
<user id='398'>
<name>foo</name>
<email>[e-mail]</name>
</user>
<user id='867'>
<name>foobar</name>
<email>[e-mail]</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. 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. 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. 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. 创建标签云

function getcloud( $data = array(), $minfontsize = 12, $maxfontsize = 30 )
{
$minimumcount = min( array_values( $data ) );
$maximumcount = 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. 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 similarity

14. 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. 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. 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. 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. 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. 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">\1</a>', $text);
$text = eregi_replace('([[:space:]()[{}])(www.[-a-za-z0-9@:%_+.~#?&//=]+)',
'\1<a href="http://\2">\2</a>', $text);
$text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',
'<a href="mailto:\1">\1</a>', $text);

return $text;
}

20. 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. 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
}