<?php
    $str = "请注意：有谁知道30901.5号路怎么走？这个因为我买了100块的烧饼和7901的钥匙了，那个对了，我再拿个30000";
    $pattern = '/(\d+\.?\d+)/';

    //$pattern = '/(\d+)\.?(\d+)/';
    // $str = "42.234 EUR 53.218 AUD CAD97.164 311.151 MYR 125.042 NZD GBP84.270 SGD60.227 USD134.400";

    if(preg_match_all($pattern, $str, $match)){
        echo '<pre>';
        print_r($match);
    }else{
        echo '没有找到！';
    }
?>

结果

Array
(
    [0] => Array
        (
            [0] => 30901
            [1] => 100
            [2] => 7901
            [3] => 30000
        )

    [1] => Array
        (
            [0] => 30901
            [1] => 100
            [2] => 7901
            [3] => 30000
        )

)