幫你解析複雜的C語言聲明

      很多C/C++的初學者，常常被一些複雜的聲明語句弄得暈頭轉向，滿頭霧水。比如說：char *(*(*a[])())()，這個聲明是什麼意思呢？

     不用抓耳撓腮，在linux環境下，有一個工具能幫我們解析，它就是cdecl 。它能在C/C++聲明和英語間轉換。讓我們先看看man cdecl裡的描述吧：

DESCRIPTION
       Cdecl  (and c++decl) is a program for encoding and decoding C (or C++) type declarations.  The C language is based on the (draft proposed) X3J11 ANSI Standard; optionally, the C language may be based on the pre- ANSI  definition  defined  by  Kernighan  &  Ritchie’s The C Programming Language book, or the C language  defined by the Ritchie PDP-11 C compiler.  The C++ language is based on Bjarne Stroustrup’s The C++  Pro-gramming Language, plus the version 2.0 additions to the language.

     很容易用：鍵入cdecl命令，進入互動介面：

# cdecl
Type `help' or `?' for help
cdecl>

這時鍵入命令：

explain char *(*(*a[])())()

看看輸出什麼了：

declare a as array of pointer to function returning pointer to function returning pointer to char
cdecl>

反過來，我們把輸出的英文當命令，再執行一次看看：

cdecl> declare a as array of pointer to function returning pointer to function returning pointer to char
char *(*(*a[])())()
cdecl>

     好用吧，如果有不明白，就help一下。

2010-12-28 於 杭州