致命错误字符串 + 字符串我该如何解决？ [复制]

Question

PHP 致命错误：未捕获的类型错误：不支持的操作数类型：字符串 + 字符串 inoverview.php:33 堆栈跟踪： #0 {主要} 在第 33 行的 C:\inetpub\wwwroot\praktijkopdrachttennis\overview.php 中抛出

<?php
    include("includes/header.php");
    //Session

    $username = "Tennisser";
    $password = "Tryhard";


if ($_POST['username'] == $username && $_POST['password'] == $password)
    {
         session_start();
         $_SESSION['login'] = true;
    }
    //Foutieve inlog
    else
         {
             echo "<a href='inlogpage.php'>Foutieve inlog, probeer het opnieuw./a>";
         }
//Code voor login true
    if ($_SESSION['login'] == true)
        {
            $leden = array ('Tim', 'Jur', 'Alba');

            $beschikbaarheid = array (3/5, 7/10, 12/3);

            $dagdelen = array ('Middag', 'Ochtend', 'Nacht');

            $countedmembers = count($leden);

            for ($i = 0; $i <= $countedmembers ; $i++ )
            {
                echo "<tr>";
                echo "<td>" + $leden[$i] + "</td>";
                echo "<td>" + $beschikbaarheid[$i] + "</td>";
                echo "<td>" + $dagdelen[$i] + "</td>";
            }
        }

?>

Answer 1

只需使用点. 作为连接运算符而不是加+

<?php
  
// First String
$a = 'Hello';
  
// Second String
$b = 'World!';
  
// Concatenation Of String
$c = $a.$b;
  
// print Concatenate String
echo " $c \n";
?>