Php 将变量作为变量传递给url时出错

我正在尝试将会话变量传递到变量“var”中的url。我对此不熟悉，请帮助我解决下面第7行代码中的问题

php

           if($user){
                 $response["error"] = false;
                 $_SESSION['vault_no'] = $user['vault_no'];

                $to=$email;
                $subject = "Reset profile password";
                $txt = "Click on link to reset your profile password-> www.miisky.com/appmiisky/reset_pro.php?var = $_SESSION['vault_no']" ;
                $headers =  'From: innovation@miisky.com' . "\r\n" ;
                $headers .= "BCC: prajwalkm7@gmail.com\r\n";
                $headers .=  'Reply-To: innovation@miisky.com' . "\r\n" .
                 'X-Mailer: PHP/' . phpversion(); 
                /*$headers = 'From: innovation@miisky.com' . "\r\n" .
                            'Cc: innovation@miisky.com' . "\r\n" .
               'Reply-To: innovation@miisky.com' . "\r\n" .
                'X-Mailer: PHP/' . phpversion();*/

                mail($to,$subject,$txt,$headers);
                 echo json_encode($response);
            }

---

双引号（“）内的所有文本都作为字符串

$txt = "Click on link to reset your profile password-> www.miisky.com/appmiisky/reset_pro.php?var = $_SESSION['vault_no']" ;

您需要使用字符串联系会话值以获取url

$txt = "Click on link to reset your profile password-> www.miisky.com/appmiisky/reset_pro.php?var=" . $_SESSION['vault_no'];

---

双引号（“）内的所有文本都作为字符串

$txt = "Click on link to reset your profile password-> www.miisky.com/appmiisky/reset_pro.php?var = $_SESSION['vault_no']" ;

您需要使用字符串联系会话值以获取url

$txt = "Click on link to reset your profile password-> www.miisky.com/appmiisky/reset_pro.php?var=" . $_SESSION['vault_no'];

---

reset_pro.php？var=“.$\u SESSION['vault_no']；

您遇到了什么错误？您能展示一下您的输出（电子邮件）的实际情况吗？感谢大家的响应..！问题已经解决了DrajDeep paul sir..！！很抱歉我没提到这个问题。！错误是->“语法错误，意外”（T_ENCAPSED_和_空格），需要标识符（T_STRING）或变量（T_variable）或数字“

reset_pro.php？var=“.$\u SESSION['vault_no']；

您遇到了什么错误？您能展示一下您的输出（电子邮件）的实际情况吗？感谢大家的响应..！问题已经解决了DrajDeep paul先生..！！很抱歉我没提到这一点。！错误是->“语法错误，意外”（T_封装的_和_空格），应为标识符（T_字符串）或变量（T_变量）或数字“