php的功能(18)

　　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) {