解碼正則表達式

Question

我正在尋找解碼正則表達式。 有沒有一種方法來檢查下面的正則表達式的意思：

^(PC([Y\\d])|GC([Y\\d])|Y|\\d)\\d{4,5}$ 

Answer 1

你可以在http://www.myezapp.com/apps/dev/regexp/show.ws使用正則表達式分析器或http://www.debuggex.com/

---

^ = start of string 
() = capturing groups 
[] = character classes 
\d = digit in 0-9 
\\ = literal backslash 
| = OR 
{} = count of leading item 
$ = end of string 

Answer 2

這裏是一個向下突破的發生了什麼。

正則表達式：^(PC([Y\\d])|GC([Y\\d])|Y|\\d)\\d{4,5}$

1.^  - Beginning of line 
2. (  - Beginning of a capture group 
3. PC  - Finds `PC` exactly 
4. ([Y\\d]) - Creates a capture group for a Y or a single digit (0-9) 
5. |  - This is an OR statement 
6. GC  - Finds `GC` exactly 
7. ([Y\\d]) - Same as 4 
8. |  - This is an OR statement 
9. Y  - Finds `Y` exactly 
10. |  - This is an OR statement 
11. \\d  - This looks for a single digit (0-9) 
12.)  - End of capture group. Lines 3-11 will be in this capture group 
13. \\d{4,5} - This will look any digit exactly 4 or 5 times 
14. $  - End of line 

有這3個捕獲組：

1. (PC([Y\\d])|GC([Y\\d])|Y|\\d) 
2. ([Y\\d]) (The first one) 
3. ([Y\\d]) (The second one) 

這裏，我只是用123456來說明如何有效匹配（任意數量會被發現的列表有很多地方可以）：

• PCY1234
• PCY12345
• PCY1234
• PCY12345
• PC12345
• PC123456
• GC12345
• GC123456
• GCY1234
• GCY12345
• Y1234
• Y12345

Here是具有用於每個匹配捕獲基團的解釋來RegExr的鏈接。

此外，中雙\的原因是爲了逃避用於Java的\。並不是所有的語言都需要這個，據我所知，有一些需要3.如果你注意到上面的RegExr，我刪除了它們，RegExr會正確解析正則表達式。

Answer 3

Regexper也是分析正則表達式的好工具。