PHP：正則表達式，preg_split

Question

我有一個像這樣的內容的字符串。

19. Which of the following conflicting criteria does the problem below satisfe. 2.1 
C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 
a. Writability vs Readability 
b. Reliability vs Cost of execution 
c. Writability vs Reliability 
d. Cost of execution vs. Readability 
e. Cost of execution vs. Readability 

我想要做的就是像這樣拆分它。

[0] => 19. Which of the following conflicting criteria does the problem below satisfye. 2.1 
C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 

    [1] => a. Writability vs Readability 

    [2] => b. Reliability vs Cost of execution 

    [3] => c. Writability vs Reliability 

    [4] => d. Cost of execution vs. Readability 

    [5] => e. Cost of execution vs. Readability 

我的正則表達式很弱，我有這種結果。

preg_split('/(?=[a-e\d]+\.(?!\d))/', $entries, -1, PREG_SPLIT_NO_EMPTY); 

    [0] => 1 
    [1] => 9. Which of the following conflicting criteria does the problem below satisfy 
    [2] => e. 2.1 
C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 

    [3] => a. Writability vs Readability 

    [4] => b. Reliability vs Cost of execution 

    [5] => c. Writability vs Reliability 

    [6] => d. Cost of execution vs. Readability 

    [7] => e. Cost of execution vs. Readability 

我應該怎麼做？

Answer 1

據我所知，如果有^[a-e\d]+\.ahead（從下面一行開始），您想要在一個或多個\v垂直空格處進行拆分。 preg_split功能是好的：

$pattern = '/\v+(?=^[a-e\d]+\.)/m'; 

m是爲了使^插入符號匹配行開始（不只是字符串開始）的多標誌。

print_r(preg_split($pattern, $str)); 

test at eval.in;應該給出期望的結果：

Array 
(
    [0] => 19. Which of the following conflicting criteria does the problem below satisfe. 2.1 
C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 
    [1] => a. Writability vs Readability 
    [2] => b. Reliability vs Cost of execution 
    [3] => c. Writability vs Reliability 
    [4] => d. Cost of execution vs. Readability 
    [5] => e. Cost of execution vs. Readability 
) 

還有see regex101用於測試分割序列。如果中間有空格的空行，請嘗試使用\s+（一個或多個空格）而不是\v+。

Answer 2

如果你只是想打破每行了......

$str = "19. Which of the following conflicting criteria does the problem below satisfe. 2.1 C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 
a. Writability vs Readability 
b. Reliability vs Cost of execution 
c. Writability vs Reliability 
d. Cost of execution vs. Readability 
"; 

preg_match_all('/(.*)\n/', $str, $matches); 

var_dump($matches); 

會給你

array(2) { 
    [0]=> 
    array(5) { 
     [0]=> 
     string(169) "19. Which of the following conflicting criteria does the problem below satisfe. 2.1 C++ pointers are powerful and very flexible but at the cost of poor intelligibility. 
     " 
     [1]=> 
     string(32) "a. Writability vs Readability 
     " 
     [2]=> 
     string(38) "b. Reliability vs Cost of execution 
     " 
     [3]=> 
     string(32) "c. Writability vs Reliability 
     " 
     [4]=> 
     string(39) "d. Cost of execution vs. Readability 
     " 
    } 
    [1]=> 
    array(5) { 
     [0]=> 
     string(168) "19. Which of the following conflicting criteria does the problem below satisfe. 2.1 C++ pointers are powerful and very flexible but at the cost of poor intelligibility." 
     [1]=> 
     string(31) "a. Writability vs Readability" 
     [2]=> 
     string(37) "b. Reliability vs Cost of execution" 
     [3]=> 
     string(31) "c. Writability vs Reliability" 
     [4]=> 
     string(38) "d. Cost of execution vs. Readability" 
    } 
} 

preg_match_all()會給您匹配多行的模式和$matches陣列的能力會給你所有的比賽。由於它會將整行（包括\ n）視爲匹配，所以這是第一個數組。所以你需要(.*)匹配的部分，它位於$matches數組的第二個元素中。