在c ++ / cli中设置一个指向指针的指针

问题描述

我有一个托管类，想在<div class="modal" id="createMessageModal" tabindex="-1" role="dialog"> <div class="modal-dialog modal-xl" role="document"> <div class="modal-content"> @using (Html.BeginForm("Dashboard","App",null,FormMethod.Post,new { @id = "frmSendMessage",@name = "frmSendMessage" })) { <div class="modal-header"> <h5 class="modal-title">Send Message</h5> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">&times;</span> </button> </div> <div class="modal-body"> <table> <tbody> <tr> <th style="padding-bottom:15px">From:</th> @Html.HiddenFor(model => model.messageSenderID) <td style="padding-bottom:15px;">@ViewBag.Name</td> </tr> <tr> <th style="padding-bottom:15px">To:</th> <td style="width:100% !important; padding-bottom: 15px;"> @Html.DropDownListFor(model => model.messageRecipientID,Model.messageRecipientsDropdown,"Select A Recipient",new { @id = "recipient",@name = "recipient",@class = "form-control" }) @Html.ValidationMessageFor(model => model.messageRecipientID,"",new { @class = "text-danger" }) </td> </tr> <tr> <th>Subject:</th> <td style="width:100% !important">@Html.TextBoxFor(model => model.messageSubject,new { @class = "form-control",@name = "messageSubject",@id = "messageSubject" })</td> <td>@Html.ValidationMessageFor(model => model.messageSubject,new { @class = "text-danger" })</td> </tr> </tbody> </table> <br /> @Html.TextAreaFor(model => model.messageBody,new { rows = "15",style = "resize:none; min-width:100%;",id = "messageBody",name = "messageBody" }) @Html.ValidationMessageFor(model => model.messageBody,new { @class = "text-danger" }) </div> <div class="modal-footer"> <button type="submit" class="btn btn-primary">Send Message</button> <button type="button" class="btn btn-secondary" data-dismiss="modal">Cancel</button> </div> } </div> </div> </div> 方法中设置本机类。

$(document).ready(function() {
  $("#frmSendMessage").submit(function() {
    Recipient = $("input[name='recipient']").val();
    MessageSubject = $("input[name='messageSubject']").val();
    MessageBody = $("input[name='messageBody']").val();


    return false;
  })
});

但是，运行create()时会删除ref class ManagedClass { private: NativeClass* ptr = nullptr; public: void create() { NativeClass nativeClass; nativeClass.set(0); this->ptr = &nativeClass; } }; 。因此nativeClass为空。如何使局部变量create()不被删除？

解决方法

当定义了局部变量的函数返回时，局部变量将不复存在，并且任何记住的指向该局部变量的指针都将变为无效。 C ++ / CLI与非托管C ++没什么不同。

要创建在create调用之后仍然存在的对象，请动态分配该对象并使用ptr = new NativeClass();保存指向它的指针（然后，在不再需要时不要忘记delete ptr;）