我是PHP的新手，但是具有php / html和数据库的基本知识。
以前从未使用$ _SESSION函数。
这是为网站开发网页/主页/索引页。 但我得到错误 我对$ _SESSION不太了解，无法从数组中获取索引是我可以在搜索中找到的几个示例，但与$ _SESSION无关
<?php
session_start();
include("connection.php");
$sqlsettings = "SELECT * from admin";
$resultsettings = mysqli_query($conn,$sqlsettings);
$rowsettings = mysqli_fetch_array($resultsettings,MYSQLI_BOTH);
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<?php include("common/includes_static.php"); ?>
<?php include("common/constants.php"); ?>
<title><? echo $kSiteName." - ".$kSiteTitle; ?></title>
</head>
<body style="margin: 0px;">
<a name="Matrimonials"></a>
<a name="Matrimonial"></a>
<center>
<div class="width">
</div>
<br style="line-height: 0px;" clear="all">
<div class="smallcnt width">
<div class="left tleft">
<font style="font-size:26pt;"><span class="orangeText" style="">Marry</span><span class="redText"style="font-weight:bold">Soulmate</span></font>
<br>
<div class="left tleft" style="padding-left:30px"> <span style="color: rgb(170, 170, 170);"><?php echo $kSiteTitle; ?> </span></span><br><br></div>
</div>
</div>
<div class="smallcnt width">
<div class="left tleft">
</div>
<!-- FORM ST -->
<div class="right tright" style="width: 192px;"><!-- right top header --></div><br clear="all">
<!-- FORM EN-->
</div>
<div class="smallcnt width" style=" background-image:url(images/topbg.gif); -moz-background-clip: initial; -moz-background-origin: initial; -moz-background-inline-policy: initial;">
<div class="left tleft" style="width: 33px;"><img src="images/top-lft-cnl.gif" border="0" height="33" width="14"><br></div>
<div class="left tleft" style="">
<?php
**if($_SESSION['UserID']!="")**
{
?>
<br>
<a href="index.php" title="My Account" style="color:#FFFFFF;"><strong>Home</strong></a> <strong style="color:#FFFFFF;">|</strong> <a href="compatibility.php" title="My Account" style="color:#FFFFFF;"><strong>Compatibility Check</strong></a> <strong style="color:#FFFFFF;">|</strong> <a href="contactus.php" title="Log Out" style="color:#FFFFFF;"><strong>Contact Us</strong></a><strong style="color:#FFFFFF;">|</strong>
<a href="myaccount.php" title="My Account" style="color:#FFFFFF;"><strong>My Account</strong></a> <strong style="color:#FFFFFF;">|</strong> <a href="my_profile.php" title="My Profile" style="color:#FFFFFF;"><strong>My Profile</strong></a> <strong style="color:#FFFFFF;">|</strong> <a href="logout.php" title="Log Out" style="color:#FFFFFF;"><strong>Log Out</strong></a>
<?php
}
else
{
?>
<form method="post" action="login.php" name="loginpage" autocomplete="off" style="margin: 4px 0pt 0pt 0px;">
<b><a href="index.php" style="color:#FFFFFF;border-right:1px solid #FFF;padding-right:5px">Home</a> | <a href="aboutus.php" style="color:#FFFFFF;border-right:1px solid #FFF;padding-right:5px">About Us</a> | <a href="contactus.php" style="color:#FFFFFF;border-right:1px solid #FFF;padding-right:5px">Contact Us</a> </b> <b style="color:#FFFFFF;padding-left:20px">Member Login</b> <input name="login" value="Email ID" onfocus="if(this.value=='Email ID') this.value='';" onblur="if(this.value=='') this.value='Email ID';" size="30" type="text"> <input name="password" value="*****" onfocus="if(this.value=='*****') this.value='';" onblur="if(this.value=='') this.value='*****';" size="14" type="password"> <input style="border:none" src="images/go.gif" title="Login" align="top" border="0" type="image"><input name="homepage" value="Y" type="hidden"><input name="continue" value="true" type="hidden"> <a href="forget_password.php" class="xsmall" title="Forgot Password?" style="color:#FFFFFF;">Forgot Password?</a>
</form>
<?php
}
?>
</div>
<!-- FORM ST -->
<br clear="all">
<!-- FORM EN-->
</div>
<div class="width smallcnt">
<!-- MAIN CREATIVE ST-->
<div style="width: 760px; padding-top: 0px;">
<table border="0" cellpadding="0" cellspacing="0" width="760">
<tr>
<td width="291" valign="top">
<fieldset>
<table style="padding-left:10px" border="0" cellpadding="0" cellspacing="0" align="left">
<?php include("sections/searchbox.php"); ?>
</tr>
<tr>
<td>
<!-- SEARCH FORM ST-->
<div style="padding-left:5px; text-align: left;">
<form method="get" action="<?php
if($_SESSION['UserID']!="")
{
echo "profile.php";
}
else
{
echo "login.php";
}
?>" autocomplete="off" name="profileform">
<br/>
<br/>
<input name="id" value=" Search by Profile ID" onfocus="if(this.value==' Search by Profile ID') this.value='';" onblur="if(this.value=='') this.value=' Search by Profile ID';" style="width: 111px;" type="text">
<input style="border:none" src="images/go.gif" title="View Profile" align="top" type="image">
</form>
<br/><br/>
</div>
<!-- SEARCH FORM EN-->
</td>
</tr>
</table>
<br/>
</fieldset>
</td>
<td ><img src="images/banner.jpg" ></td>
</tr></table>
</div>
<!-- MAIN CREATIVE EN-->
</div>
<!-- REGISTER/UPGRADE CONTENT ST-->
<div class="width smallcnt" style="border-top: 1px solid rgb(255, 255, 255); background: transparent url(images/main-bg.gif) repeat-x scroll left top; -moz-background-clip: initial; -moz-background-origin: initial; -moz-background-inline-policy: initial;">
<div id="threeStep" class="left tleft">
<div id="step1" class="left" style="border-right: 1px solid rgb(255, 255, 255); width: 184px; height: 67px;" onmouseover="change_image(1,'rollin','images/');" onmouseout="change_image(1,'rollout','images/')">
<div style="padding-top: 13px;">
<a href="register.php"><img id="digit1" src="images/one-off.gif" alt="" align="left" border="0" height="43" hspace="13" width="43"></a> <a href="register.php"><font style="color:#FFF7E0; font-family:Arial, Helvetica, sans-serif; font-size:16px; font-weight:bold;">Register</font></a><br><a href="register.php" style="color:#606060;">
and create your<br> free profile.</a>
</div>
</div>
<div id="step2" class="left" style="border-right: 1px solid rgb(255, 255, 255); width: 184px; height: 67px;" onmouseover="change_image(2,'rollin','images/');" onmouseout="change_image(2,'rollout','images/');">
<div style="padding-top: 13px;">
<a href="search.php" style="color:#606060;"><img id="digit2" src="images/two-off.gif" alt="" align="left" border="0" height="43" hspace="13" width="43"><font style="color:#FFF7E0; font-family:Arial, Helvetica, sans-serif; font-size:16px; font-weight:bold;">Search</font><br>
for members who<br> meet your criteria.</a>
</div>
</div>
<div id="step3" class="left" style="border-right: 1px solid rgb(255, 255, 255); width: 184px; height: 67px;" onmouseover="change_image(3,'rollin','images/');" onmouseout="change_image(3,'rollout','images/');">
<div style="padding-top: 13px;">
<a href="communicate.php" style="color:#606060;"><img id="digit3" src="images/three-off.gif" alt="" align="left" border="0" height="43" hspace="13" width="43">
<font style="color:#FFF7E0; font-family:Arial, Helvetica, sans-serif; font-size:16px; font-weight:bold;">Contact</font><br>
members you like via<br>email or phone.</a>
</div>
</div>
</div><!-- three step en -->
<div class="left" style="padding: 20px 0pt 0pt 36px;">
<a href="register.php"><img src="images/advSearcButton.png" alt="Register Free!" title="Register Free!" border="0" height="30" vspace="0" width="140"></a>
</div>
<br clear="all">
</div>
<div class="width smallcnt" style="background-image:url(images/background.jpg)">
<div class="left graytxt" style=""></div>
<div class="left graytxt" style="width: 760px">
<table cellspacing="0" cellpadding="0" border="0" class="left tleft smallcnt graytxt" style="padding: 10px; border: 1px solid #FFBD7B;">
<tr>
<td>
<p style="font-size:12px;color:#A35804;font-weight:normal;text-align:justify;font-family:Sans-Serif,Verdana">
<?php
if($_SESSION['UserID']!="")
{
echo "<a href='membership.php'>";
}
else
{
echo "<a href='paidmembership.php'>";
}
?>
<img src="images/offer.gif" style="float:right;padding-left:10px;padding-right:10px;padding-bottom:10px" border="0" /> </a>
We aspire to make the match making genuine and hasslefree.
<br/><br/>
There are so many doctors,engineers, lecturers, dentists and other professionals in our community. But there are very few affordable matrimonial.
This is a platform for those searching for their life partners and is dedicated for all community people who are looking for soul mates
<br/><br/>
We aim to provide service at a very affordable price (starting at <b>Rs.500</b> only). We would be glad to hear from you!
</p>
</td>
</tr>
</table>
</div>
</div><br clear="all">
</div><span class="brseven"><br>
<!-- Footer starts -->
<?php
include("footer.php");
?>
<!-- Footer ends -->
</span></center>
</body></html>
第59行出现错误，该错误为 if（$ _ SESSION ['UserID']！=“”）
请帮助我解决此问题以及此类错误的原因。在我的其余代码中，我可能也会遇到很多此类错误