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为什么使用引用而不是指针？(Why use references rather than pointers?)

 当没有对引用进行编译时类型检查时，为什么要使用引用而不是指针？  
 想象一下，你正在创建一个Person类型的对象，需要持有一个引用/指针到他们的House （非常随机） - 所以person对象将把house引用/指针作为数据成员。 想象一下，这是通过参考完成的：  
class Person{
   public:
      Person(House& myHouse) : house(myHouse) { }
   private:
      House& house;
};
 
 我看到的问题是，如果您忘记在数据成员声明中包含＆，那么您认为是引用的内容将成为副本。 当然，传递和保存指针会更安全，所以这个错误会在编译时被标记出来吗？  
 我没有说明使用其中一个 - 我问为什么引用用于指针来保存数据成员？ 

Why to use references rather than pointers when there is no compile time type checking on references? 
Imagine that you are creating an object of type Person that needs to hold a reference/pointer to their House (pretty random) - so the person object would hold the house reference/pointer as a data member. Imagine this was done with references: 
class Person{
   public:
      Person(House& myHouse) : house(myHouse) { }
   private:
      House& house;
};
 
The issue I see though is if you forget to include the & in the data member declaration that thing you thought was a reference becomes a copy. Surely it would be safer to pass and save a pointer so this error would be flagged up at compile time? 
I'm not making a point to use one or the other - I'm asking why are references used over pointers to save data members?

原文：https://stackoverflow.com/questions/15045863

更新时间：2023-11-24 09:11

最满意答案

 我认为在你的select标签中th：值不正确，id没有正确设置。  
 即对于监护人来说应该是这样的  
<select th:field="*{guardian}">
      <option th:each="guardian : ${guardians}" 
             th:value="${guardian.id}" 
             th:text="${guardian.name}"></option>
</select>
 
 对于timeLapse应该这样声明  
<select th:field="*{timeLapse}">
     <option th:each="timeLapse : ${timeLapses}" 
         th:value="${timeLapse.id}" 
         th:text="${timeLapse.description}"></option>
</select>  
 
 而对于关卡，我认为你通过了错误的领域，即它可能看起来像那样  
<select th:field="*{level}" multiple="multiple">
             <option th:each="level : ${alarmLevels}" 
                 th:value="${level}" 
                 th:text="${level}"></option>
        </select>
 
 我希望这有帮助。 

I think that in your select tags the th:value is not correct, the id is not set correctly. 
ie for the guardian it should be like this 
<select th:field="*{guardian}">
      <option th:each="guardian : ${guardians}" 
             th:value="${guardian.id}" 
             th:text="${guardian.name}"></option>
</select>
 
for the timeLapse is should be declared like that 
<select th:field="*{timeLapse}">
     <option th:each="timeLapse : ${timeLapses}" 
         th:value="${timeLapse.id}" 
         th:text="${timeLapse.description}"></option>
</select>  
 
and for the level I think that you passed the wrong field ie it might look like that 
<select th:field="*{level}" multiple="multiple">
             <option th:each="level : ${alarmLevels}" 
                 th:value="${level}" 
                 th:text="${level}"></option>
        </select>
 
I hope this helps.

为什么使用引用而不是指针？(Why use references rather than pointers?)

最满意答案

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