难以识别出错误的原因。已删除所有空白区域。使用CodeAnywhere作为我的IDE，因为它是我的要求。任何帮助，将不胜感激。
完整错误：
Warning: Cannot modify header information - headers already sent by (output started at /home/cabox/workspace/Project/ShoppingCart.php:134) in /home/cabox/workspace/Project/ShoppingCart.php on line 169
代码：
<?php
session_start();
$connect = mysqli_connect("localhost", "root", "", "lab"); //connect to the db
if(isset($_POST["add_to_cart"])) //if the add to cart value is set
{
if(isset($_SESSION["shopping_cart"])) //if the shopping cart session is set
{
$item_array_id = array_column($_SESSION["shopping_cart"], "item_id");
//if there are values in your shopping cart loop through and display them
if(!in_array($_GET["id"], $item_array_id))
{
$count = count($_SESSION["shopping_cart"]);
$item_array = array(
'item_id' => $_GET["id"],
'item_name' => $_POST["hidden_name"],
'item_price' => $_POST["hidden_price"],
'item_quantity' => $_POST["quantity"]
);
$_SESSION["shopping_cart"][$count] = $item_array;
}
else
{
echo '<script>alert("Item Already Added")</script>';
//restriction on design - can only add one instance of each product, delete if you want to add more
}
}
else
{
$item_array = array(
'item_id' => $_GET["id"],
'item_name' => $_POST["hidden_name"],
'item_price' => $_POST["hidden_price"],
'item_quantity' => $_POST["quantity"]
);
$_SESSION["shopping_cart"][0] = $item_array;
}
}
if(isset($_GET["action"]))
{
if($_GET["action"] == "delete")
//when you select 'Remove', delete the values based on id. Alert box will show on completition
{
foreach($_SESSION["shopping_cart"] as $keys => $values)
{
if($values["item_id"] == $_GET["id"])
{
unset($_SESSION["shopping_cart"][$keys]);
echo '<script>alert("Item has been removed from Shopping Cart")</script>';
echo '<script>window.location="ShoppingCart.php"</script>';
}
}
}
}
?>
<!DOCTYPE html>
<html>
<head>
<title>Shopping Cart</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
<!-- AJAX is about loading data in the background and display it on the webpage, without reloading the whole page.-->
<link rel="stylesheet" type="text/css" href="thePerfectPair.css" />
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<script>
// Get the modal
var modal = document.getElementById('id01');
// When the user clicks anywhere outside of the modal, close it
window.onclick = function(event) {
if (event.target == modal) {
modal.style.display = "none";
}
}
</script>
</head>
<body>
<nav class="navigationBar">
<!--Establishing the top left hand side of the Navigation Bar-->
<div class="leftTopNavBar">
€ EUR |
<!--The following produces a pop up sign up form that is validated through javascript functions in the following code.
I implemented this pop up form to create a different design element as opposed to just referring users to another page.
All design element are assigned in the css file and it involved calling many different classes in order not to conflict
with other forms and input boxes contained in the website-->
<button onclick="document.getElementById('id01').style.display='block'" style="width:auto;" class="SignUpBtn0">SIGN UP |</button>
<div id="id01" class="modal">
<span onclick="document.getElementById('id01').style.display='none'" class="close" title="Close Modal">×</span>
<form class="modal-content" action="/action_page.php">
<div class="container1">
<h1>Sign Up</h1>
<p>Please fill in this form to create an account with Perfect Pair!</p>
<hr>
<b>Email</b>
<input type="text" placeholder="Enter Email" name="email" required>
<b>Password</b>
<input type="password" placeholder="Enter Password" name="psw" required>
<b>Repeat Password</b>
<input type="password" placeholder="Repeat Password" name="psw-repeat" required>
<label>
<input type="checkbox" checked="checked" name="remember" style="margin-bottom:15px"> Remember me</label>
<p>By creating an account you agree to our <a href="#" style="color:dodgerblue">Terms & Privacy</a>.</p>
<div class="clearfix">
<button type="button" onclick="document.getElementById('id01').style.display='none'" class="cancelbtn">Cancel</button>
<button type="submit" class="signupbtn">Sign Up</button>
</div>
</div>
</form>
</div>
SAVED ITEMS
</div>
<!--Establishing the right side of the navBar-->
<div class="rightTopNavBar">
<input type="search" placeholder="Search..." name="search">
<button type="submit"><i class="fa fa-search"></i></button>
<a href="LogIn.php">LOGIN |</a> CART
<i class="fa fa-shopping-cart" style="font-size:20px"></i>
</div>
<!--Establishing the middle of the navBar-->
<div class="middleTopNavBar">
<a href="ShoeHomePage.php"><img src="Images/perfectPairLogo.png" class="logoHeader" alt="logo" width="100" height="100"></a>
</div>
<!--Establishing bottom navBar-->
<div class="bottomNavBar">
<a href="ShoeHomePage.php" style="text-decoration:none"> <i class="fa fa-home" style="font-size:36px"> </i></a>
<a href="Heels.php" style="text-decoration:none"> HEELS </a>
<a href="Sandals.php" style="text-decoration:none"> SANDALS </a>
<a href="Boots.php" style="text-decoration:none"> BOOTS </a>
<a href="Trainers.php" style="text-decoration:none"> TRAINERS </a>
<a href="Flats.php" style="text-decoration:none"> FLATS </a>
<a href="ShoppingCart.php" style="text-decoration:none"> SHOPPING CART </a></div></nav>
<div class="container">
<br><?php $query="SELECT*FROM tbl_product1 ORDER BY id ASC"; $result=mysqli_query($connect, $query); if(mysqli_num_rows($result)>0){while($row=mysqli_fetch_array($result)){?><div class="col-md-4">
<form method="post" class="phpForm" action="ShoppingCart.php?action=add&id=<?php echo $row["id"];?>" >
<div class="formStyleDiv" style=" background-color:#f1f1f1; border-radius:1px; padding:16px; width:25%;" align="center">
<img src="Images/<?php echo $row["image"];?>" class="img-responsive" style="height: 200px;" />
<h4 class="text-info"><?php echo $row["name"];?></h4><br />
<h4 class="text-danger">€<?php echo $row["price"];?></h4>
<input type="text" name="quantity" value="1" class="form-control" />
<input type="hidden" name="hidden_name" value="<?php echo $row["name"];?>" />
<input type="hidden" name="hidden_price" value="<?php echo $row["price"];?>" />
<input type="submit" name="add_to_cart" style="margin-top:5px;" class="submitBtn" class="btn btn-success" value="Add to Cart" /></div>
</form>
</div><?php
}
}
?><div style="clear:both"></div>
<br />
<h3>Order Details</h3>
<div class="table-responsive" >
<table>
<tr>
<th width="40%" align="left">Item Name</th>
<th width="10%" align="left">Quantity</th>
<th width="20%" align="left">Price</th>
<th width="15%" align="left">Total</th>
<th width="5%" align="left">Action</th>
</tr><?php if(!empty($_SESSION["shopping_cart"])) { $total = 0; foreach($_SESSION["shopping_cart"] as $keys => $values){?><tr>
<td><?php echo $values["item_name"];?></td>
<td><?php echo $values["item_quantity"];?></td>
<td>€<?php echo $values["item_price"];?></td>
<td>€<?php echo number_format($values["item_quantity"] * $values["item_price"], 2);?></td>
<td><a href="ShoppingCart.php?action=delete&id=<?php echo $values["item_id"];?>"><span class="text-danger">Remove</span></a></td>
</tr><?php $total = $total + ($values["item_quantity"] * $values["item_price"]);}?><tr>
<td colspan="3" align="right">Total</td>
<td align="right">€<?php echo number_format($total, 2); ?></td>
<td></td>
</tr><?php $cookie_name="Total"; setcookie($cookie_name, $total, time()+(86400*30),"/");}?></table></div>
<input type="button" class="submitFormBtn" name="submit" value= "Submit" onclick="window.open ('success.php','_self',false)" /><br />
</div>
</div>
<br />
</body>
</html>