如何将某些字符与正则表达式匹配？

Question

I have string "image(100)" , i want filter the string to remove image and the parentheses then return just the number 100 .

i have tried /[^image]/ and image removed, but i don't know how to remove parenthesis .

Answer 1

要只替换非数字，什么都没有，就像这样：

echo preg_replace('/\D/', '', 'image(100)');

Answer 2

You need to escape parentheses with a backslash, as they are special characters in regular expressions. Here I use them to capture the number and save it to the $matches array .

<?php
$str = "image(100)";
if (preg_match("/image\((\d+)\)/", $str, $matches)) {
    echo $matches[1];
}