一些常用的php函数

1.产生随机字符串函数

<?php
function random($length) {
$hash = '';
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz';
$max = strlen($chars) - 1;
mt_srand((double)microtime() * 1000000);
for($i = 0; $i < $length; $i++) {
$hash .= $chars[mt_rand(0, $max)];
}
return $hash;
}
?>

2.截取一定长度的字符串

注：该函数对GB2312使用有效

<?php
function wordscut($string, $length ,$sss=0) {
if(strlen($string) > $length) {
               if($sss){
                      $length=$length - 3;
                      $addstr=' ...';
                }
  for($i = 0; $i < $length; $i++) {
   if(ord($string[$i]) > 127) {
    $wordscut .= $string[$i].$string[$i + 1];
    $i++;
   } else {
    $wordscut .= $string[$i];
   }
  }
  return $wordscut.$addstr;

}
return $string;
}
?>

3.取得客户端IP地址

<?php
function GetIP(){
             if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
                   $ip = getenv("HTTP_CLIENT_IP");
             else if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
                   $ip = getenv("HTTP_X_FORWARDED_FOR");
             else if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
                   $ip = getenv("REMOTE_ADDR");
             else if (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))
                   $ip = $_SERVER['REMOTE_ADDR'];
             else
                  $ip = "unknown";
             return($ip);
}
?>

4.创建相应的文件夹

<?php
function createdir($dir='')
{
        if (!is_dir($dir))
        {
            $temp = explode('/',$dir);
            $cur_dir = '';
            for($i=0;$i<count($temp);$i++)
            {
                $cur_dir .= $temp[$i].'/';
                if (!is_dir($cur_dir))
                {
                @mkdir($cur_dir,0777);
                }
            }
        }
}
?>

5.判断邮箱地址

<?php
function checkEmail($inAddress)
{
return (ereg("^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(\.[a-zA-Z0-9_-])+",$inAddress));
}
?>

6.跳转

<?php
function gotourl($message='',$url='',$title='')
{

    $html  ="<html><head>";
    if(!empty($url))
     $html .="<meta http-equiv='refresh' content=\"3;url='".$url."'\">";
    $html .="<link href='../templates/style.css' type=text/css rel=stylesheet>";
    $html .="</head><body><br><br><br><br>";
    $html .="<table cellspacing='0' cellpadding='0' border='1' width='450' align='center'>";
$html .="<tr><td bgcolor='#ffffff'>";
$html .="<table border='1' cellspacing='1' cellpadding='4' width='100%'>";
$html .="<tr class='m_title'>";
$html .="<td>".$title."</td></tr>";
$html .="<tr class='line_1'><td align='center' height='60'>";
$html .="<br>".$message."<br><br>";
    if (!empty($url))
     $html .="系统将在3秒后返回<br>如果您的浏览器不能自动返回,请点击[<a href=".$url." target=_self>这里</a>]进入";
    else
     $html .="[<a href='#' onclick='history.go(-1)'>返回</a>]";
    $html .="</td></tr></table></td></tr></table>";
$html .="</body></html>";
echo $html;
exit;
}
?>

7.分页（两个函数配合使用）

<?php
function getpage($sql,$page_size=20)
{
      global $page,$totalpage,$sums;  //out param
      $page = $_GET["page"];
      //$eachpage = $page_size;
      $pagesql = strstr($sql," from ");
      $pagesql = "select count(*) as ids ".$pagesql;
      $result = mysql_query($pagesql);
      if($rs = mysql_fetch_array($result)) $sums = $rs[0];
      $totalpage = ceil($sums/$page_size);
      if((!$page)||($page<1)) $page=1;
   $startpos = ($page-1)*$page_size;
   $sql .=" limit $startpos,$page_size ";
    return $sql;
}

function showbar($string="")
{
    global $page,$totalpage;
$out="共<font color='red'><b>".$totalpage."</b></font>页  ";
    $linkNum =4;
    $start = ($page-round($linkNum/2))>0 ? ($page-round($linkNum/2)) : "1";
    $end   = ($page+round($linkNum/2))<$totalpage ? ($page+round($linkNum/2)) : $totalpage;
    $prestart=$start-1;
    $nextend=$end+1;
    if($page<>1)
$out .= "<a href='?page=1&&".$string."'title=第一页>第一页</a> ";
    if($start>1)
$out.="<a href='?page=".$prestart."' title=上一页>..<<</a> ";
for($t=$start;$t<=$end;$t++)
    {
     $out .= ($page==$t) ? "<font color='red'><b>[".$t."]</b></font> " : "<a href='?page=$t&&".$string."'>$t</a> ";
    }
if($end<$totalpage)
$out.="<a href='?page=".$nextend."&&".$string."' title=下一页>>>..</a>";
    if($page<>$totalpage)
   $out .= " <a href='?page=".$totalpage."&&".$string."' title=最后页>最后页</a>";
   return $out;
}