常用函数php

//随机数
/**
 * @param int $length 随机数长度
 * @param string $num 是否只包含数字
 * @return null|string 返回随机字符串
 */
function codestr($length=4,$num=''){
    $str    = null;
    $strPol = $num==1 ? '123456789' : "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
    $max    = strlen($strPol)-1;
    for($i=0;$i<$length;$i++){
        $str.=$strPol[rand(0,$max)];//rand($min,$max)生成介于min和max两个数之间的一个随机整数
    }
    return $str;
}
/**
 * @param $obj
 * @return mixed
 * 对象转换为数组
 */
function objToArray($obj){
    return json_decode(json_encode($obj),true);
}

/**
 * 字符串截取
 * @param $str
 * @param int $start
 * @param $length
 * @param string $charset
 * @param bool|true $suffix
 * @return string
 */
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true) {
    if(function_exists("mb_substr"))
        $slice = mb_substr($str, $start, $length, $charset);
    elseif(function_exists('iconv_substr')) {
        $slice = iconv_substr($str,$start,$length,$charset);
        if(false === $slice) {
            $slice = '';
        }
    }else{
        $re['utf-8']   = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
        $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
        $re['gbk']    = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
        $re['big5']   = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
        preg_match_all($re[$charset], $str, $match);
        $slice = join("",array_slice($match[0], $start, $length));
    }
    return $suffix ? $slice.'...' : $slice;
}

/**
 * @param $list
 * @param string $pk
 * @param string $pid
 * @param string $child
 * @param int $root
 * @return array
 * 无限分类 数组转 树形结构
 */
function list_to_tree($list, $pk='id', $pid = 'pid', $child = '_child', $root = 0) {
    // 创建Tree
    $tree = array();
    if(is_array($list)) {
        // 创建基于主键的数组引用
        $refer = array();
        foreach ($list as $key => $data) {
            $refer[$data[$pk]] =& $list[$key];
        }
        foreach ($list as $key => $data) {
            // 判断是否存在parent
            $parentId =  $data[$pid];
            if ($root == $parentId || (isset($data['spid'])&&$data['pid'].'|' == $data['spid'])) {
                $tree[$data[$pk]] =& $list[$key];
            }else{
                if (isset($refer[$parentId])) {
                    $parent =& $refer[$parentId];
                    $parent[$child][$data[$pk]] =& $list[$key];
                }
            }
        }
    }
    return $tree;
}

/**
 * @param $str
 * @return string
 * 密码加密
 */
function passwordEncode($str,$code=''){
    return sha1($code.md5($str));
}
/**
 * @param $mobile
 * @return bool
 * 验证手机号码是否正确
 */
function is_mobile($mobile){
    $reg = '/^1[34578][0-9]{9}$/';
    if(!preg_match($reg,$mobile)){
        return false;
    }
    return true;
}
function isUrl($url)
{
    $reg = '/^http[s]?:\/\/[_a-zA-Z0-9-]+(.[_a-zA-Z0-9-]+)*$/';
  if(!preg_match($reg,$url)){
      return false;
  }
    return true;
}
function isEmail($email){
    return filter_var($email,FILTER_VALIDATE_EMAIL);
}

/**
 * 将数组转换为字符串
 *
 * @param    array    $data        数组
 * @param    bool    $isformdata    如果为0，则不使用new_stripslashes处理，可选参数，默认为1
 * @return    string    返回字符串，如果，data为空，则返回空
 */
function array2string($data, $isformdata = 1) {
    if($data == '') return '';
    if($isformdata) $data = new_stripslashes($data);
    return addslashes(var_export($data, TRUE));
}
function new_addslashes($string){
    if(!is_array($string)) return addslashes($string);
    foreach($string as $key => $val) $string[$key] = new_addslashes($val);
    return $string;
}

/**
 * 返回经stripslashes处理过的字符串或数组
 * @param $string 需要处理的字符串或数组
 * @return mixed
 */
function new_stripslashes($string) {
    if(!is_array($string)) return stripslashes($string);
    foreach($string as $key => $val) $string[$key] = new_stripslashes($val);
    return $string;
}
/**
 * 创建目录
 *
 * @param    string    $path    路径
 * @param    string    $mode    属性
 * @return    string    如果已经存在则返回true，否则为flase
 */
function dir_create($path, $mode = 0777) {
    if(is_dir($path)) return TRUE;
    $ftp_enable = 0;
    $path = dir_path($path);
    $temp = explode('/', $path);
    $cur_dir = '';
    $max = count($temp) - 1;
    for($i=0; $i<$max; $i++) {
        $cur_dir .= $temp[$i].'/';
        if (@is_dir($cur_dir)) continue;
        @mkdir($cur_dir, 0777,true);
        @chmod($cur_dir, 0777);
    }
    return is_dir($path);
}
function dir_path($path) {
    $path = str_replace('\\', '/', $path);
    if(substr($path, -1) != '/') $path = $path.'/';
    return $path;
}
/**
 * 取得文件扩展
 *
 * @param $filename 文件名
 * @return 扩展名
 */
function fileext($filename) {
    return strtolower(trim(substr(strrchr($filename, '.'), 1, 10)));
}
/**
 * 返回经htmlspecialchars处理过的字符串或数组
 * @param $obj 需要处理的字符串或数组
 * @return mixed
 */
function new_html_special_chars($string) {
    $encoding = 'utf-8';
    //if(strtolower(CHARSET)=='gbk') $encoding = 'ISO-8859-15';
    if(!is_array($string)) return htmlspecialchars($string,ENT_QUOTES,$encoding);
    foreach($string as $key => $val) $string[$key] = new_html_special_chars($val);
    return $string;
}