如何阅读抽象编程信息

I had a test yesterday and I found myself having to understand something I had no knowledge about.

我昨天接受了测试,发现自己必须了解一些我不了解的事情。

Please see the following page:

请参阅以下页面:

declaration-list:
  declaration
  declaration-list declaration 
declaration-specifiers:
  storage-class-specifier declaration-specifiersopt
  type-specifier declaration-specifiersopt
  type-qualifier declaration-specifiersopt 
storage-class specifier: one of
  auto register static extern typedef 
type specifier: one of
  void char short int long float double signed
  unsigned struct-or-union-specifier enum-specifier typedef-name 
type-qualifier: one of
  const volatile 
struct-or-union-specifier:
  struct-or-union identifieropt { struct-declaration-list }
  struct-or-union identifier 
struct-or-union: one of
  struct union 
struct-declaration-list:
  struct declaration
  struct-declaration-list struct declaration 
init-declarator-list:
  init-declarator
  init-declarator-list, init-declarator 
init-declarator:
  declarator
  declarator = initializer 
struct-declaration:
  specifier-qualifier-list struct-declarator-list; 
specifier-qualifier-list:
  type-specifier specifier-qualifier-listopt
  type-qualifier specifier-qualifier-listopt 
struct-declarator-list:
  struct-declarator
  struct-declarator-list , struct-declarator 
struct-declarator:
  declarator
  declaratoropt : constant-expression 
enum-specifier:
  enum identifieropt { enumerator-list }
  enum identifier

This is from the book "The C Programming Language" by Brian W. Kernighan Dennis M. Ritchie but I saw it on the internet and on many other books.

这是由Brian W. Kernighan Dennis M. Ritchie撰写的“The C Programming Language”一书,但我在网上和许多其他书籍上看过它。

I tried googling it but frankly, I have no Idea how is it called so I couldn't find any relevant information. Our professors have never tought us to read it and I now believe it's extremely important to know how to read it.

我试着谷歌搜索它,但坦率地说,我不知道如何调用它,所以我找不到任何相关信息。我们的教授从来没有想过我们阅读它,我现在相信知道如何阅读它是非常重要的。

I'm looking for reference to guides or a short explanation on how to approach it.

我正在寻找指南的参考或如何处理它的简短说明。

I apologize if that's a repost but I couldn't find any related post.

如果这是一个转发,我道歉,但我找不到任何相关的帖子。

2 个解决方案

#1

It is called the syntax notation. It is described in C11 6.1:

它被称为语法表示法。它在C11 6.1中描述:

In the syntax notation used in this clause, syntactic categories (nonterminals) are indicated by italic type, and literal words and character set members (terminals) by bold type. A colon (:) following a nonterminal introduces its definition. Alternative definitions are listed on separate lines, except when prefaced by the words ''one of''. An optional symbol is indicated by the subscript _opt, so that

在本节中使用的语法表示法中,语法类别(非终结符号)由斜体类型表示,文字单词和字符集成员(终端)以粗体表示。非终结符后面的冒号(:)引入了它的定义。替代定义列在单独的行中,除非以“其中一个”开头。可选符号由下标opt表示,因此

{ expression_opt}

{expressionsopt}

indicates an optional expression enclosed in braces.

表示括在大括号中的可选表达式。

So, to take the first non-terminal as an example:

所以,以第一个非终端为例:

declaration-list:
declaration
declaration-list declaration

声明列表:声明声明列表声明

means that a declaration-list is a single declaration, or alternatively a declaration-list followed by a single declaration (i.e. it would define itself recursively).

表示声明列表是单个声明,或者声明列表后跟单个声明(即它将递归地定义自身)。

By the way, these declaration-lists are the old and long obsolete way how function parameters were typed in C:

顺便说一句,这些声明列表是在C中输入函数参数的旧的和过时的过时方式:

some_function(a, b)
    int a;
    double b;
{
    printf("a = %d, b = %f\n", a, b);
}

The int a; double b; part is the optional declaration-list, and double b; is a single declaration. So the declaration-list is defined recursively as being a declaration list that is of one declaration, or a declaration list that is followed by a declaration.

int a;双b; part是可选的声明列表,双b;是一个单一的声明。因此,声明列表以递归方式定义为一个声明列表,该声明列表是一个声明,或声明列表后跟一个声明。

To actually internalize meaning to these syntactic constructs, you'd better read the C11 standard draft n1570 online or the PDF version. Note also, that the grammar just gives the syntax of a C program, but the constraints and semantics of the C program are written in text.

为了实际内化这些句法结构的含义,你最好阅读在线的C11标准草案n1570或PDF版本。另请注意,语法只是给出了C程序的语法,但C程序的约束和语义是用文本编写的。

#2

The first definition...

第一个定义......

declaration-list:
    declaration
    declaration-list declaration

...can be read as: "A declaration-list is either a declaration or a declaration-list followed by a declaration."

...可以理解为:“声明列表是声明或声明列表,后跟声明。”

This recursive definition allows for the following as examples of a declaration-list:

此递归定义允许以下作为声明列表的示例:

declaration
declaration declaration
declaration declaration declaration

声明声明

etc.

The full grammar definition will contain additional rules describing what makes up a valid declaration, and so on.

完整的语法定义将包含描述构成有效声明的内容的其他规则,依此类推。

#1