主要是（）A pre-定义的C函数？ [英] Is main() a pre-defined function in C?

问题描述

可能重复：结果
  的main（）在C，C ++，Java和C＃

我在一般新的节目，和C中尤其如此。我看有一个主功能每个实例 - 这是$ P $以某种方式对定义，这样的名字呈现出特殊意义的编译器或运行时......还是仅仅是一个常见的​​成语C程序员之间（比如使用foo和酒吧任意变量名）。

I'm new to programming in general, and C in particular. Every example I've looked at has a "main" function - is this pre-defined in some way, such that the name takes on a special meaning to the compiler or runtime... or is it merely a common idiom among C programmers (like using "foo" and "bar" for arbitrary variable names).

推荐答案

没有，您需要定义主在你的程序。由于它是由运行时调用，但是，接口的主必须提供为pre定义（必须返回 INT ，必须采取零个参数或两个，第一个 INT ，第二一个的char ** 或等价地，的char * [] ）。 C和C ++标准并指定具有外部链接的功能，名为主充当入口点计划 ¹ 。

No, you need to define main in your program. Since it's called from the run-time, however, the interface your main must provide is pre-defined (must return an int, must take either zero arguments or two, the first an int, and the second a char ** or, equivalently, char *[]). The C and C++ standards do specify that a function with external linkage named main acts as the entry point for a program¹.

目前至少与期限一般使用时，predefined功能将是诸如罪或的printf 这是标准库，所以你可以使用它，而不必自己动手写。

At least as the term is normally used, a predefined function would be one such as sin or printf that's in the standard library so you can use it without having to write it yourself.

¹ 如果你想获得的技术，这是唯一真正的托管的实施 - 即那种我们大多数人使用最多的产生，一个操作系统上运行的程序的时候。 A自立的实施（一个产生直接在裸机下它没有操作系统运行程序）是免费的，因为它认为合适的定义的入口点（S）。一项独立的实现也可以离开了最正常的运行时库，只提供头极少数（如＆LT; STDDEF.H＆GT; ），几乎没有标准库函数。

¹If you want to get technical, that's only true for a "hosted" implementation -- i.e., the kind most of us use most of the time that produces programs that run on an operating system. A "free-standing" implementation (one produces program that run directly on the "bare metal" with no operating system under it) is free to define the entry point(s) as it sees fit. A free-standing implementation can also leave out most of the normal run-time library, providing only a handful of headers (e.g., <stddef.h>) and virtually no standard library functions.

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