preg_match來檢查字符串是否有特定的結構

Question

如果字符串有特定的結構，如何用php與preg_match()進行檢查。例如字符串是：

options:blue;white;yellow; 

我要檢查，如果字符串與字符串，然後:隨後通過;

分隔的字符串的正數和東西是重要的開始 - 字符串可以採用西裏爾字母，不僅拉丁字母

Answer 1

假設只有在你的問題中所列的限制都需要，這將驗證字符串：

$number = 3; 
$regex = sprintf('/^[^:]+:(?:[^;]+;){%d}$/', $number); 

if (preg_match($regex, $string)) { 
    echo "It matches!"; 
} else { 
    echo "It doesn't match!"; 
} 

下面是它在行動的例子，用php -a：

php > $number = 3; 
php > $regex = sprintf('/^[^:]+:(?:[^;]+;){%d}$/', $number); 

php > if (preg_match($regex, 'options:blue;white;yellow;')) { 
php {  echo "It matches!"; 
php { } else { 
php {  echo "It doesn't match!"; 
php { } 
It matches! 

php > if (preg_match($regex, 'options:blue;white;yellow;green;')) { 
php {  echo "It matches!"; 
php { } else { 
php {  echo "It doesn't match!"; 
php { } 
It doesn't match! 

你可以想像這個表達式here。讓我們來分解它：

/.../   Start and end of the pattern. 
^    Start of the string. 
[^:]+   At least one character that is not a ':'. 
:    A literal ':'. 
(?:[^;]+;){N} Exactly N occurrences of: 
        [^;]+ At least one character that is not a ';'. 
        ;  A literal ';'. 
$    End of the string.