问题描述
这两个声明有区别吗？
int foo( int a, ... );
和
int foo( int a ... );
如果没有区别，使第二个语法有效的意义是什么？
If there is no difference, what was the point of making the second syntactically valid?
推荐答案
这是猜测，但在C ++中可以有一个没有其他参数的函数，例如 void f（...）而在C中这样的函数没有使用（我知道）所以 ...
This is speculation, but in C++ in can make sense to have a function with no other parameters, e.g. void f(...) whereas in C a function like this has no use (that I know of) so ... must follow some other parameter and hence, a comma.
从语法的角度来看，简单地允许 void f int a ...），并赋予它明显的意义，而不是不允许它，它不会导致编译器编写器的任何负担或任何混乱的程序员。
From a grammar point of view, it's simpler to simply allow void f( int a ... ) and give it the obvious meaning than it is to disallow it and it's not going to cause much of a burden on compiler writers or any confusion for programmers.
（我原来认为这可能与使参数包的语法更规则，但我发现它是明确允许在任何情况下C ++ 03）。
(I originally thought it might be something to do with making the grammar for parameter packs more regular but I discovered that it was explicitly allowed in C++03 in any case.)
这篇关于为什么逗号在C ++可变函数声明中是可选的？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！