正确声明在ANSI C的main（）函数

问题描述

C标准说：

However, Kernighan & Ritchie in their second edition (the canonical ANSI C) bible just use:

main()
{
  /* taram pampam ... */

  return 0;
}

Who is right?Does it have to do with function without return value automatic assume to be returning int in C?

解决方案

Well, if you want ANSI C, then by definition the standard is right.

In C89/C90 the int return type is implied, so the K&R definition would be acceptable.

In C99 this is no longer the case.

The C90 standard has the following wording (5.1.2.2.1 Program startup), which is very similar to the C99 wording (probably most significantly it uses the less strong 'can' instead of 'shall'):

There's nothing in that section directly about the fact that leaving off the return type will result in it defaulting to int.

Frankly, I have a hard time finding exactly where that behavior is specified by the standard. The closest I can come is in 6.7.1 (Functions definitions) where the grammar for function definitions indicates that the 'declaration-specifiers' are optional, and the examples say:

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