C++变量类型——顺时针螺旋移动法

C++有个令人头痛的点是会出现一些极其复杂的变量声明，比如：

string(const** f(int, void (*const p)(int)))(char[]);

这会让人难以判断这个变量是什么类型。最近发现一个顺时针螺旋移动法则，感觉对于C++变量类型的确定很有用。

顺时针螺旋移动法

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顺时针螺旋移动法的原文介绍和举例

一、主要步骤

1. 重要的语法解释：

• [X] or []: Array X size of... or Array undefined size of...

• (type1, type2): function passing type1 and type2 returning...

• *: pointer(s) to...

2. 确定变量名，将其作为顺时针螺旋的起点

3. 按照顺时针螺旋路径遍历所有修饰符

4. 遇到括号，先遍历完括号内中的内容

二、举例解释

1.char *str[10]

                     +-------+
                     | +-+   |
                     | ^ |   |
                char *str[10];
                 ^   ^   |   |
                 |   +---+   |
                 +-----------+

• str is an...
• str is an array 10 of...
• str is an array 10 of pointers to...
• str is an array 10 of pointers to char

2.char *(*fp)( int, float *)

                     +--------------------+
                     | +---+              |
                     | |+-+|              |
                     | |^ ||              |
                char *(*fp)( int, float *);
                 ^   ^ ^  ||              |
                 |   | +--+|              |
                 |   +-----+              |
                 +------------------------+

• fp is a...
• fp is a pointer to...
• fp is a pointer to a function passing an int and a pointer to float returning...
• fp is a pointer to a function passing an int and a pointer to float returning a pointer to...
• fp is a pointer to a function passing an int and a pointer to float returning a pointer to a char

3.void (*signal(int, void (*fp)(int)))(int)

                      +-----------------------------+
                      |                  +---+      |
                      |  +---+           |+-+|      |
                      |  ^   |           |^ ||      |
                void (*signal(int, void (*fp)(int)))(int);
                 ^    ^      |      ^    ^  ||      |
                 |    +------+      |    +--+|      |
                 |                  +--------+      |
                 +----------------------------------+

• signal is a function passing an int and a...
  • fp is a pointer to...
  • fp is a pointer to a function passing int returning...
  • fp is a pointer to a function passing int returning nothing (void)
• signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning...
• signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to...
• signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to a function passing an int returning...
• signal is a function passing an int and a pointer to a function passing an int returning nothing (void) returning a pointer to a function passing an int returning nothing (void)