在C ++中将对象数组设置为null [英] Set array of object to null in C++

问题描述

假设我在C ++中有一个Foo类型的对象数组:

Suppose I have an array of objects of type Foo in C++:

Foo array[10];

在Java中，可以通过以下方式简单地将此数组中的对象设置为null:

In Java, I can set an object in this array to null simply by:

array[0] = null //the first one

如何在C ++中做到这一点?

How can I do this in C++?

推荐答案

使用指针代替:

Foo *array[10];

// Dynamically allocate the memory for the element in `array[0]`
array[0] = new Foo();
array[1] = new Foo();

...

// Make sure you free the memory before setting 
// the array element to point to null
delete array[1]; 
delete array[0]; 

// Set the pointer in `array[0]` to point to nullptr
array[1] = nullptr;
array[0] = nullptr;

// Note the above frees the memory allocated for the first element then
// sets its pointer to nullptr. You'll have to do this for the rest of the array
// if you want to set the entire array to nullptr.

请注意，您需要考虑使用C ++进行内存管理，因为与Java不同，它没有垃圾收集器，当您设置对nullptr的引用时，该垃圾收集器会自动为您清除内存.另外，nullptr是一种现代且正确的C ++实现方法，因为指针类型并非总是零，而不是总是零.

Note that you need to consider memory management in C++ because unlike Java, it does not have a Garbage Collector that will automatically clean up memory for you when you set a reference to nullptr. Also, nullptr is the modern and proper C++ way to do it, as rather than always is a pointer type rather than just zero.

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