一 代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <Meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>应用正则表达中的点字符（.）</title> <style type="text/css"> <!-- body { margin-left: 0px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; } --> </style></head> <body> <?PHP $checkip="/^(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])(\.)(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])(\.)(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])(\.)(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])$/"; if($_POST[check_ip]!="" and $_POST[Submit]=="提交"){ if(preg_match($checkip,$_POST[check_ip],$counts)){ echo "<script>alert('IP地址格式正确!');window.location.href='index.PHP';</script>"; }else{ echo "<script>alert('IP地址格式不正确!');window.location.href='index.PHP';</script>"; } } ?> <table width="851" height="483" border="0" align="center" cellpadding="0" cellspacing="0" background="images/bg.jpg"> <tr> <td height="119" colspan="3"> </td> </tr><form id="form1" name="form1" method="post" action="index.PHP"> <tr> <td width="336" height="264"> </td> <td width="260" align="center" valign="top">IP地址： <input type="text" name="check_ip" /></td> <td width="255" valign="top"><input type="submit" name="Submit" value="提交" /></td> </tr></form> <tr> <td height="100"> </td> <td> </td> <td> </td> </tr> </table> </body> </html>
二 运行结果
输入：56.06.45.33
输出：IP地址格式不正确
