原始C语言背后的一个基本原则是，内存是由一系列字节组成的，代码只需要关心这些字节在被使用的确切时刻意味着什么。现代C语言允许编译器施加额外的限制，但C语言包括——c++保留了——将指针分解为字节序列，将包含相同值的任何字节序列组装为指针，然后使用该指针访问先前的对象。

While that ability can be useful--or even indispensable--in some kinds of applications, a language that includes that ability will be very limited in its ability to support any kind of useful and reliable garbage collection. If a compiler doesn't know everything that has been done with the bits that made up a pointer, it will have no way of knowing whether information sufficient to reconstruct the pointer might exist somewhere in the universe. Since it would be possible for that information to be stored in ways that the computer wouldn't be able to access even if it knew about them (e.g. the bytes making up the pointer might have been shown on the screen long enough for someone to write them down on a piece of paper), it may be literally impossible for a computer to know whether a pointer could possibly be used in the future.

An interesting quirk of many garbage-collected frameworks is that an object reference not defined by the bit patterns contained therein, but by the relationship between the bits held in the object reference and other information held elsewhere. In C and C++, if the bit pattern stored in a pointer identifies an object, that bit pattern will identify that object until the object is explicitly destroyed. In a typical GC system, an object may be represented by a bit pattern 0x1234ABCD at one moment in time, but the next GC cycle might replace all references to 0x1234ABCD with references to 0x4321BABE, whereupon the object would be represented by the latter pattern. Even if one were to display the bit pattern associated with an object reference and then later read it back from the keyboard, there would be no expectation that the same bit pattern would be usable to identify the same object (or any object).

什么类型?它应该针对嵌入式洗衣机控制器、手机、工作站或超级计算机进行优化吗? 它应该优先考虑gui响应还是服务器加载? 它应该使用大量内存还是大量CPU?

C/c++被用于太多不同的环境。 我怀疑像增强智能指针这样的东西对大多数用户来说就足够了

编辑:自动垃圾收集器并不是一个性能问题(你总是可以购买更多的服务器)，而是一个可预测的性能问题。 不知道GC什么时候会起作用就像雇佣一个嗜睡症的飞行员，大多数时候他们是很棒的-但当你真的需要响应的时候!

主要有两个原因:

因为它不需要(恕我直言) 因为它与RAII几乎不兼容，RAII是c++的基石

c++已经提供了手动内存管理、堆栈分配、RAII、容器、自动指针、智能指针……这应该足够了。垃圾收集器适合懒惰的程序员，他们不想花5分钟思考谁应该拥有哪些对象或什么时候应该释放资源。这不是我们在c++中做事情的方式。

强制垃圾收集实际上是一个低级到高级的范式转换。

If you look at the way strings are handled in a language with garbage collection, you will find they ONLY allow high level string manipulation functions and do not allow binary access to the strings. Simply put, all string functions first check the pointers to see where the string is, even if you are only drawing out a byte. So if you are doing a loop that processes each byte in a string in a language with garbage collection, it must compute the base location plus offset for each iteration, because it cannot know when the string has moved. Then you have to think about heaps, stacks, threads, etc etc.

If you want automatic garbage collection, there are good commercial and public-domain garbage collectors for C++. For applications where garbage collection is suitable, C++ is an excellent garbage collected language with a performance that compares favorably with other garbage collected languages. See The C++ Programming Language (4rd Edition) for a discussion of automatic garbage collection in C++. See also, Hans-J. Boehm's site for C and C++ garbage collection (archive). Also, C++ supports programming techniques that allow memory management to be safe and implicit without a garbage collector. I consider garbage collection a last choice and an imperfect way of handling for resource management. That does not mean that it is never useful, just that there are better approaches in many situations.

来源:http://www.stroustrup.com/bs_faq.html垃圾收集

至于为什么它没有内置它，如果我没记错的话，它是在GC出现之前发明的，我不相信这种语言有GC，有几个原因(我不相信它有GC)。C)向后兼容。

希望这能有所帮助。

要回答关于c++的大多数“为什么”问题，请阅读c++的设计与进化