在我运行项目时，我会遇到这样的错误消息
警告：session_start（）：无法发送会话缓存限制器-标头 已发送（输出始于 C：\ xampp \ htdocs \ skripsieka \ file1.php：125）在 第2行上的C：\ xampp \ htdocs \ skripsieka \ file2.php
这是什么原因？以及如何解决
此代码
<!DOCTYPE html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>SPK topsis</title>
<!-- plugins:css -->
<link rel="stylesheet" href="assets/vendors/mdi/css/materialdesignicons.min.css">
<link rel="stylesheet" href="assets/vendors/css/vendor.bundle.base.css">
<!-- endinject -->
<!-- Plugin css for this page -->
<!-- End plugin css for this page -->
<!-- inject:css -->
<!-- endinject -->
<!-- Layout styles -->
<link rel="stylesheet" href="assets/css/style.css">
<!-- End layout styles -->
<link rel="shortcut icon" href="assets/images/favicon.png" />
</head>
<?php
if(@$_GET['a']=='kriteria'){
$active1='class="active"';
$active2='';
$active3='';
$active4='';
}else if(@$_GET['a']=='alternatif'){
$active1='';
$active2='class="active"';
$active3='';
$active4='';
}else if(@$_GET['a']=='nilaimatrik'){
$active1='';
$active2='';
$active3='class="active"';
$active4='';
}else if(@$_GET['a']=='hasiltopsis'){
$active1='';
$active2='';
$active3='';
$active4='class="active"';
}else{
$active1='';
$active2='';
$active3='';
$active4='';
}
?>
<div class="container-scroller">
<!-- partial:partials/_navbar.html -->
<nav class="navbar default-layout-navbar col-lg-12 col-12 p-0 fixed-top d-flex flex-row">
<div class="text-center navbar-brand-wrapper d-flex align-items-center justify-content-center">
<a class="navbar-brand brand-logo" href="index.html"><img src="assets/images/logo.svg" alt="logo" /></a>
<a class="navbar-brand brand-logo-mini" href="index.html"><img src="assets/images/logo-mini.svg" alt="logo" /></a>
</div>
<div class="navbar-menu-wrapper d-flex align-items-stretch">
<button class="navbar-toggler navbar-toggler align-self-center" type="button" data-toggle="minimize">
<span class="mdi mdi-menu"></span>
</button>
<div class="search-field d-none d-md-block">
<form class="d-flex align-items-center h-100" action="#">
<div class="input-group">
<div class="input-group-prepend bg-transparent">
<i class="input-group-text border-0 mdi mdi-magnify"></i>
</div>
<input type="text" class="form-control bg-transparent border-0" placeholder="Search projects">
</div>
</form>
</div>
<ul class="navbar-nav navbar-nav-right">
<li class="nav-item nav-logout d-none d-lg-block">
<a class="nav-link" href="logout.php">
<i class="mdi mdi-power"></i>
</a>
</li>
</ul>
</div>
</nav>
<!-- partial -->
<div class="container-fluid page-body-wrapper">
<!-- partial:partials/_sidebar.html -->
<nav class="sidebar sidebar-offcanvas" id="sidebar">
<ul class="nav">
<li class="nav-item nav-profile">
<a href="#" class="nav-link">
<div class="nav-profile-image">
<img src="assets/images/faces/face1.jpg" alt="profile">
<span class="login-status online"></span>
<!--change to offline or busy as needed-->
</div>
<div class="nav-profile-text d-flex flex-column">
<span class="font-weight-bold mb-2">Admin</span>
<span class="text-secondary text-small">eka amaliyah</span>
</div>
<i class="mdi mdi-bookmark-check text-success nav-profile-badge"></i>
</a>
</li>
<li <?php echo $active1 ?> class="nav-item">
<a class="nav-link" href="?a=kriteria&k=kriteria" >
<span class="menu-title">Kriteria</span>
<i class="mdi mdi-home menu-icon"></i>
</a>
</li>
<li <?php echo $active2 ?> class="nav-item">
<a class="nav-link" data-toggle="collapse" href="?a=alternatif&k=alternatif" aria-expanded="false" aria-controls="ui-basic">
<span class="menu-title">Data Kepala Keluarga</span>
<i class="menu-arrow"></i>
<i class="mdi mdi-crosshairs-gps menu-icon"></i>
</a>
</li>
<li <?php echo $active3 ?> class="nav-item">
<a class="nav-link" href="?a=nilaimatrik">
<span class="menu-title">Nilai matriks</span>
<i class="mdi mdi-contacts menu-icon"></i>
</a>
</li>
<li <?php echo $active4 ?> class="nav-item">
<a class="nav-link" href="?a=hasiltopsis&k=nilai_matriks">
<span class="menu-title">Hasil Topsis</span>
<i class="mdi mdi-format-list-bulleted menu-icon"></i>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="pages/charts/chartjs.html">
<span class="menu-title">Charts</span>
<i class="mdi mdi-chart-bar menu-icon"></i>
</a>
</li>
</ul>
</nav>
<!-- partial -->
<div class="main-panel">
<div class="content-wrapper">
<div class="col-12 grid-margin">
<div class="card">
<div class="card-body">
<?php
if(@$_GET['a']=='kriteria'){
include ("kriteria.php");
}else if(@$_GET['a']=='alternatif'){
include ("alternatif.php");
}else if(@$_GET['a']=='nilaimatrik'){
include ("nilaimatrik.php");
}else if(@$_GET['a']=='hasiltopsis'){
include ("hasiltopsis.php");
}
?>
</div>
</div>
</div>
<!-- content-wrapper ends -->
<!-- partial:partials/_footer.html -->
<footer class="footer">
<div class="d-sm-flex justify-content-center justify-content-sm-between">
<span class="text-muted text-center text-sm-left d-block d-sm-inline-block">Copyright © 2020 <a href="https://www.bootstrapdash.com/" target="_blank">Eka amaliyah</a>. All rights reserved.</span>
<span class="float-none float-sm-right d-block mt-1 mt-sm-0 text-center">I made it with <i class="mdi mdi-heart text-danger"></i></span>
</div>
</footer>
<!-- partial -->
</div>
<!-- main-panel ends -->
</div>
<!-- page-body-wrapper ends -->
</div>
<!-- TAB KIRI -->
<!-- /TAB KIRI -->
<
</div>
<!-- container-scroller -->
<!-- plugins:js -->
<script src="../../assets/vendors/js/vendor.bundle.base.js"></script>
<!-- endinject -->
<!-- Plugin js for this page -->
<!-- End plugin js for this page -->
<!-- inject:js -->
<script src="../../assets/js/off-canvas.js"></script>
<script src="../../assets/js/hoverable-collapse.js"></script>
<script src="../../assets/js/misc.js"></script>
<!-- endinject -->
<!-- Custom js for this page -->
<!-- End custom js for this page -->
</body>
</html>
这是发生错误时的页面
<?php
session_start();
include ("konfig/koneksi.php");
$s=mysqli_query($conn,"select * from kriteria");
$h=mysqli_num_rows($s);
?>
<div class="box-header">
<h3 class="box-title " >Jarak Solusi Ideal Positif (D<sup>+</sup>)</h3>
</div>
<table class="table table-bordered table-responsive">
<thead>
<tr>
<th >Nomor</th>
<th >Nama</th>
<th >D<sup>+</sup></th>
</tr>
</thead>
<tbody>
<?php
//buat array kolom
$i2=1;
$i3=0;
$maxarray=array();
$a2=mysqli_query($conn,"select * from kriteria");
echo "<tr>";
while($da2=mysqli_fetch_assoc($a2)){
$idalt2=$da2['id_kriteria'];
//ambil nilai
$n2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idalt2'");
$jarakp2=0;
$c2=0;
$ymax2=array();
while($dn2=mysqli_fetch_assoc($n2)){
$idk2=$dn2['id_kriteria'];
//nilai kuadrat
$nilai_kuadrat2=0;
$k2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk2' ");
while($dkuadrat2=mysqli_fetch_assoc($k2)){
$nilai_kuadrat2=$nilai_kuadrat2+($dkuadrat2['nilai']*$dkuadrat2['nilai']);
}
//hitung jml alternatif
$jml_alternatif2=mysqli_query($conn,"select * from alternatif");
$jml_a2=mysqli_num_rows($jml_alternatif2);
//nilai bobot kriteria (rata")
$bobot2=0;
$tnilai2=0;
$k22=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk2' ");
while($dbobot2=mysqli_fetch_assoc($k22)){
$tnilai2=$tnilai2+$dbobot2['nilai'];
}
$bobot2=$tnilai2/$jml_a2;
//nilai bobot input
$b2=mysqli_query($conn,"select * from kriteria where id_kriteria='$idk2'");
$nbot2=mysqli_fetch_assoc($b2);
$bot2=$nbot2['bobot'];
$v2=round(($dn2['nilai']/sqrt($nilai_kuadrat2))*$bot2,3);
$ymax2[$c2]=$v2;
$c2++;
#cek benefit atau cost
// echo $nbot2['sifat']." - ".$nbot2['nama_kriteria']."<br>";
if($nbot2['sifat']=='benefit'){
$mak2=max($ymax2);
}else{
$mak2=min($ymax2);
}#cek benefit atau cost
}
//hitung D+
foreach($ymax2 as $nymax2){
$jarakp2=$jarakp2+pow($nymax2-$mak2,2);
}
//array max
$maxarray[$i3]=max($ymax2);
//print_r($maxarray);
//print_r(max($ymax2));
$i2++;
$i3++;
}
//session array ymax
$_SESSION['ymax']=$maxarray;
//array baris//////////////////////////////////////////////////
$i=1;
$ii=0;
$dpreferensi=array();
$a=mysqli_query($conn,"select * from alternatif");
echo "<tr>";
while($da=mysqli_fetch_assoc($a)){
$idalt=$da['id_alternatif'];
//ambil nilai
$n=mysqli_query($conn,"select * from nilai_matrik where id_alternatif='$idalt'");
$jarakp=0;
$c=0;
$ymax=array();
$arraymaks=array();
while($dn=mysqli_fetch_assoc($n)){
$idk=$dn['id_kriteria'];
//nilai kuadrat
$nilai_kuadrat=0;
$k=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk' ");
while($dkuadrat=mysqli_fetch_assoc($k)){
$nilai_kuadrat=$nilai_kuadrat+($dkuadrat['nilai']*$dkuadrat['nilai']);
}
//hitung jml alternatif
$jml_alternatif=mysqli_query($conn,"select * from alternatif");
$jml_a=mysqli_num_rows($jml_alternatif);
//nilai bobot kriteria (rata")
$bobot=0;
$tnilai=0;
$k2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk' ");
while($dbobot=mysqli_fetch_assoc($k2)){
$tnilai=$tnilai+$dbobot['nilai'];
}
$bobot=$tnilai/$jml_a;
//nilai bobot input
$b2=mysqli_query($conn,"select * from kriteria where id_kriteria='$idk'");
$nbot=mysqli_fetch_assoc($b2);
$bot=$nbot['bobot'];
$v=round(($dn['nilai']/sqrt($nilai_kuadrat))*$bot,3);
$ymax[$c]=$v;
$c++;
$mak=max($ymax);
}
//hitung D+
foreach($ymax as $nymax=>$value){
$maks=$_SESSION['ymax'][$nymax];
//echo $maks." - ";
$final=sqrt($jarakp=$jarakp+pow($value-$maks,2));
//echo $jarakp." || ";
}
echo "<tr>
<td>$i</td>
<td>$da[nm_alternatif]</td>
<td>".round($final,3)."</td>
</tr>";
$dpreferensi[$ii]=round($final,3);
$_SESSION['dplus']=$dpreferensi;
//print_r($ymax);
$i++;
$ii++;
}
echo "</tr>";
?>
</tbody>
</table>
<!-- tabel min ------------------------------------------------->
<div class="box-header">
<h3 class="box-title " >Jarak Solusi Ideal Negatif (D<sup>-</sup>)</h3>
</div>
<table class="table table-bordered table-responsive">
<thead>
<tr>
<th >Nomor</th>
<th >Nama</th>
<th >D<sup>-</sup></th>
</tr>
</thead>
<tbody>
<?php
//buat array kolom
$i2=1;
$i3=0;
$minarray=array();
$a2=mysqli_query($conn,"select * from kriteria");
echo "<tr>";
while($da2=mysqli_fetch_assoc($a2)){
$idalt2=$da2['id_kriteria'];
//ambil nilai
$n2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idalt2'");
$jarakp2=0;
$c2=0;
$ymin2=array();
while($dn2=mysqli_fetch_assoc($n2)){
$idk2=$dn2['id_kriteria'];
//nilai kuadrat
$nilai_kuadrat2=0;
$k2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk2' ");
while($dkuadrat2=mysqli_fetch_assoc($k2)){
$nilai_kuadrat2=$nilai_kuadrat2+($dkuadrat2['nilai']*$dkuadrat2['nilai']);
}
//hitung jml alternatif
$jml_alternatif2=mysqli_query($conn,"select * from alternatif");
$jml_a2=mysqli_num_rows($jml_alternatif2);
//nilai bobot kriteria (rata")
$bobot2=0;
$tnilai2=0;
$k22=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk2' ");
while($dbobot2=mysqli_fetch_assoc($k22)){
$tnilai2=$tnilai2+$dbobot2['nilai'];
}
$bobot2=$tnilai2/$jml_a2;
//nilai bobot input
$b2=mysqli_query($conn,"select * from kriteria where id_kriteria='$idk2'");
$nbot2=mysqli_fetch_assoc($b2);
$bot2=$nbot2['bobot'];
$v2=round(($dn2['nilai']/sqrt($nilai_kuadrat2))*$bot2,3);
$ymin2[$c2]=$v2;
$c2++;
$min2=min($ymin2);
}
//hitung D+
foreach($ymin2 as $nymin2){
$jarakp2=$jarakp2+pow($nymin2-$min2,2);
//echo "--".$mak."---";
}
//array max
$minarray[$i3]=min($ymin2);
//print_r($maxarray);
//print_r(max($ymax2));
$i2++;
$i3++;
}
//session array ymax
$_SESSION['ymin']=$minarray;
//array baris//////////////////////////////////////////////////
$i=1;
$ii=0;
$id_alt=array();
$a=mysqli_query($conn,"select * from alternatif");
echo "<tr>";
while($da=mysqli_fetch_assoc($a)){
$idalt=$da['id_alternatif'];
//ambil nilai
$n=mysqli_query($conn,"select * from nilai_matrik where id_alternatif='$idalt'");
$jarakp=0;
$c=0;
$ymax=array();
$arraymin=array();
while($dn=mysqli_fetch_assoc($n)){
$idk=$dn['id_kriteria'];
//nilai kuadrat
$nilai_kuadrat=0;
$k=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk' ");
while($dkuadrat=mysqli_fetch_assoc($k)){
$nilai_kuadrat=$nilai_kuadrat+($dkuadrat['nilai']*$dkuadrat['nilai']);
}
//hitung jml alternatif
$jml_alternatif=mysqli_query($conn,"select * from alternatif");
$jml_a=mysqli_num_rows($jml_alternatif);
//nilai bobot kriteria (rata")
$bobot=0;
$tnilai=0;
$k2=mysqli_query($conn,"select * from nilai_matrik where id_kriteria='$idk' ");
while($dbobot=mysqli_fetch_assoc($k2)){
$tnilai=$tnilai+$dbobot['nilai'];
}
$bobot=$tnilai/$jml_a;
//nilai bobot input
$b2=mysqli_query($conn,"select * from kriteria where id_kriteria='$idk'");
$nbot=mysqli_fetch_assoc($b2);
$bot=$nbot['bobot'];
$v=round(($dn['nilai']/sqrt($nilai_kuadrat))*$bot,3);
$ymin[$c]=$v;
$c++;
$min=max($ymin);
}
//hitung D+
foreach($ymin as $nymin=>$value){
$mins=$_SESSION['ymin'][$nymin];
// echo $mins." - ";
$final=sqrt($jarakp=$jarakp+pow($value-$mins,2));
// echo $jarakp." || ";
}
echo "<tr>
<td>$i</td>
<td>$da[nm_alternatif]</td>
<td>".round($final,3)."</td>
</tr>";
//session min
$dpreferensi[$ii]=round($final,3);
$_SESSION['dmin']=$dpreferensi;
//print_r($ymin);
//ambil id alternatif
$id_alt[$ii]=$da['id_alternatif'];
$_SESSION['id_alt']=$id_alt;
$i++;
$ii++;
}
echo "</tr>";
?>
</tbody>
</table>
答案 0 :(得分：0)
当在页面的开始处未声明{{1}}并且php脚本已经发送到HTTP标头时，通常会发生此错误。您必须在页面的最开始处开始会话。
答案 1 :(得分：0)
您应该使用
if(!isset($_SESSION))
{
session_start();
}
也许可行
答案 2 :(得分：0)
检查session_start()是否写在文件顶部，并且在此之前没有打印其他任何内容。
看看您的代码，session_start()写在顶部，但可能是发生了错误，正在会话前打印该错误。请启用显示错误和错误报告的功能，以使用以下代码进行检查。
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(-1);