malloc分配的对象的动态类型是什么？ [英] What is the dynamic type of the object allocated by malloc?

问题描述

C ++标准是指动态类型（而C标准在类似上下文中指有效类型），例如

The C++ standard refers to the term "dynamic type" (and the C standard refers to "effective type" in the similar context), for example

如果程序试图通过除以下类型之外的 glvalue 访问对象的存储值，则该行为未定义：

If a program attempts to access the stored value of an object through a glvalue of other than one of the following types the behavior is undefined:

• 对象的动态类型，

但是如何确定用 malloc 分配的对象的动态类型？

But how is the dynamic type of the object allocated with malloc determined?

例如：

void *p = malloc(sizeof(int));
int *pi = (int*)p;

pi be int ？

推荐答案

动态类型：

Dynamic type:

< glvalue> （1.8），其中由glvalue表达式表示的glvalue指向

<glvalue> type of the most derived object (1.8) to which the glvalue denoted by a glvalue expression refers

malloc 是一个未初始化的存储块。该存储空间中未构建任何对象。因此它没有动态类型。

The return value of malloc is a block of uninitialized storage. No object has been constructed within that storage. And therefore it has no dynamic type.

void * 不指向一个对象，动态类型。

The void* does not point to an object, and only objects have a dynamic type.

您可以通过开始其生命周期在该存储空间中创建一个对象。但直到你这样做，它只是存储。

You can create an object within that storage by beginning its lifetime. But until you do so, it's just storage.

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