Preg_replace在所有字符之间添加不需要的空格

Question

I have an input from an HTML table. First replacing wanted spacing by '_'. Then replacing HTML tags by spacing so I can extract the information by column.

I want my output to be:

100 Request_in_progress Pending_response 789653686

Instead the output adds extra spacing like this

$testString = '<tr><td>100</td><td>Request in progress</td><td></td><td></td><td>Pending response</td><td>789653686</td><td></td><td></td><td></td></tr>';
$rmSpace = str_replace(' ', '_', $testString);

$tags = '(<td>||</td>||<tr>||</tr>||<th>||</th>)';
$result = preg_replace($tags, ' ', $rmSpace);

echo $result;

Answer 1

It happens because the regex is incorrect.

In regular expressions, the vertical bar (|) joins alternative paths.

The expression <td>||</td> means "<td> OR the empty string OR </td>" (and so on but the rest already doesn't matter).

Accordingly, your regex matches all the HTML tags it contains but it also matches the empty strings between any two consecutive characters in the input string.

The correct regex is <td>|</td>|<tr>|</tr>|<th>|</th>.

$tags = '#<td>|</td>|<tr>|</tr>|<th>|</th>#';
$result = preg_replace($tags, ' ', $rmSpace);