PHP preg replace only allow numbers

How can I modify this existing preg_replace to only allow 开发者_开发知识库numbers?

function __cleanData($c) 
{
    return preg_replace("/[^A-Za-z0-9]/", "",$c);
}

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I think you're saying you want to remove all non-numeric characters. If so, \D means "anything that isn't a digit":

preg_replace('/\D/', '', $c)

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Try this:

return preg_replace("/[^0-9]/", "",$c);

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This should do what you want:

preg_replace("/[^0-9]/", "",$c);

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In my case, I want to keep number and '.' only

return preg_replace("/[^0-9.]/", "",$c);