stripping out all characters from a string, leaving numbers

Hay, i have a string like this:

v8gn5.8gnr4nggb58gng.g95h58g.n48fn49t.t8t8t57

I want to strip out all the characters leaving just numb开发者_运维知识库ers (and .s)

Any ideas how to do this? Is there a function prebuilt?

thanks

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$str = preg_replace('/[^0-9.]+/', '', $str);

replace substrings that do not consist of digits or . with nothing.

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preg_replace('/[^0-9.]/', '', $string);

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$input = 'some str1ng 234';
$newString = preg_replace("/[^0-9.]/", '', $input);

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To satisfy my curiosity I asked about the speed of the proposed answers and as shown in preg_replace speed optimisation/ it is (much) faster to use str_replace() than preg_replace().

So you might want to use str_replace() instead.

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Here is the shortest one:

$str = preg_replace('/\D/', '', $str);

\D = all non-digits.