在C函数声明无类型参数 [英] Untyped arguments in a C function declaration

问题描述

最近我一直在看一些从史蒂芬Skiena的的算法设计手册，并已经被他的一些函数调用的语法百思不得其解。诚然，它已经有一段时间，因为在大学做C，但我从来没有遇到过非类型化的函数参数是这样的：

Recently I've been looking at the some of the C example code from the online resources of Steven Skiena's "Algorithm Design Manual" and have been baffled by the syntax of some of his function calls. Admittedly it's been a while since did C at uni but I've never encountered untyped function arguments like this:

find_path(start,end,parents)
int start;
int end;
int parents[];
{
    if ((start == end) || (end == -1))
        printf("\n%d",start);
    else {
        find_path(starts,parents[end],parents);
        printf(" %d",end);
    }
}

这是有效语法了吗？是/是有这种风格函数声明的任何好处？它似乎比参数的传统的直打字更详细。

Is this valid syntax anymore? Are / were there any benefits with this style of function declaration? It seems more verbose than the conventional inline typing of arguments.

推荐答案

他们被称为K＆安培; R样式定义。不要在新的code使用它们。即使K和ř建议你离他们远在C编程语言2ED。

They are called K&R style definitions. Don't use them in new code. Even K and R recommend that you stay away from them in "The C Programming Language 2ed".

一个音符的历史：ANSI C和更早版本的最大变化
  版本是功能是如何声明和定义。

A note of history: the biggest change between ANSI C and earlier versions is how functions are declared and defined.

的参数括号之间命名，并且其类型是
  打开左括号之前宣布;未声明的参数
  作为 INT 。

The parameters are named between the parentheses, and their types are declared before opening the left brace; undeclared parameters are taken as int.

函数原型的新语法使一个更容易
  编译器检测的参数或者它们的类型数量的错误。
  声明和定义的旧样式仍然工作在ANSI C，在
  至少在一段过渡期，但我们强烈建议您使用
  新的形式，当你有一个支持它的编译器

The new syntax of function prototypes makes it much easier for a compiler to detect errors in the number of arguments or their types. The old style of declaration and definition still works in ANSI C, at least for a transition period, but we strongly recommend that you use the new form when you have a compiler that supports it.

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