Question

如果我想验证我的字符串是否有3个或更多点（。）我会写这个正则表达式

if(preg_match("/^[\.]{3}+$/", $string){
    echo "Match!";

'因为反斜杠表示验证我的点，而{3}会说我想要的数字。如果有效的话会很简单。也许我在这里错过了什么？

Answer 1

对于ascii范围中只有一个字符，您可以使用count_chars函数返回一个数组，其中包含每个字符的出现次数：

if ( count_chars($string)[46] > 3 ) {
    ...

46是点的十进制值。

请注意，为了使其更具可读性，您可以写：

$char = ord('.');
if ( count_chars($string)[$char] > 3 ) {
    ...

Answer 2

最直接，只要求php计算点数（仅此而已）。这不会替换，它不会生成数组，也不会计算任何其他字符。

代码：（Demo）

$strings = ['This is. a. test.',
            'This is a. test.',
            'This is. a test',
            'This is a test',
            'This. is. a. test.'
           ];
foreach ($strings as $string) {
    if (($dots = substr_count($string, '.')) >= 3) {  // assign count as variable and make comparison
        echo "Yes, 3 or more dots ($string -> $dots)";
    } else {
        echo "Nope, less than 3 dots ($string -> $dots)";
    }
    echo "\n";
}

输出：

Yes, 3 or more dots (This is. a. test. -> 3)
Nope, less than 3 dots (This is a. test. -> 2)
Nope, less than 3 dots (This is. a test -> 1)
Nope, less than 3 dots (This is a test -> 0)
Yes, 3 or more dots (This. is. a. test. -> 4)

如果要检查连续是否有3个，请使用strpos()。

代码：（Demo）

$strings = ['This is. a. test.',
            'This is a........... test.',
            'This is. a test',
            'This is a test',
            'This. is... a. test.'
           ];
foreach ($strings as $string) {
    if (($offset = strpos($string, '...')) !== false) {
        echo "Yes, found 3 in a row ($string -> $offset)";
    } else {
        echo "Nope, no occurrence of 3 dots in a row ($string)";
    }
    echo "\n";
}

输出：

Nope, no occurrence of 3 dots in a row (This is. a. test.)
Yes, found 3 in a row (This is a........... test. -> 9)
Nope, no occurrence of 3 dots in a row (This is. a test)
Nope, no occurrence of 3 dots in a row (This is a test)
Yes, found 3 in a row (This. is... a. test. -> 8)

如果要指定连续存在3个点，可以使用正则表达式：

代码：（Demo）

$strings = ['This is. a.. test...',
            'This is a........... test.',
            '...This is. a.. ..test',
            'This is a test',
            'This. is... a. test.'
           ];
foreach ($strings as $string) {
    if (preg_match('~(?<!\.)\.{3}(?!\.)~', $string)) {
        echo "Yes, found an occurrence of not more than 3 dots in a row ($string)";
    } else {
        echo "Nope, no occurrence of exactly 3 dots in a row ($string)";
    }
    echo "\n";
}

输出：

Yes, found an occurrence of not more than 3 dots in a row (This is. a.. test...)
Nope, no occurrence of exactly 3 dots in a row (This is a........... test.)
Yes, found an occurrence of not more than 3 dots in a row (...This is. a.. ..test)
Nope, no occurrence of exactly 3 dots in a row (This is a test)
Yes, found an occurrence of not more than 3 dots in a row (This. is... a. test.)

Answer 3

您可以使用str_replace，而不必担心正则表达式。

str_replace('.', '', 'one.two.three.', $count);
echo $count;

https://3v4l.org/Rl6Se

Preg_match捕获点（。）超过3次

3 个答案: