PHP正则表达式忽略字符串中的负数

I've looked all over the place, but I can't seem to only return the first positive, real number. So far, I have successfully found how to find the first positive or negative number and also only find the first negative number. Below are the two I did correctly and the one I can't get.

$str1 = "-ABS-.-179.3333es-k15dk825.44f";

1) Find first real number in string:

preg_match("/-?((\.\d+)|(\d+(\.\d+)?))/", $str1, $matches) // <- GOOD!
Expected output: -179.3333
Actual output: -179.3333

2) Find first, negative real number in string:

preg_match("/-((\.\d+)|(\d+(\.\d+)?))/", $str1, $matches) // <- GOOD!
Expected output: -179.3333
Actual output: -179.3333

3) Find first, positive real number in string:

preg_match("/(?<!-)((\.\d+)|(\d+(\.\d+)?))/", $str1, $matches) //<- WRONG!
Expected output: 15
Actual output: 79.3333

Any help is greatly appreciated!

Try the following and see if it does what you want.

preg_match_all('/[^\-\d\.]((?:\d+)(?:(?:\.\d+)|(?:\d+)))/', $str1, $matches);

var_dump($matches[1]);

I think you're looking for:

preg_match('/(?<!-|\d|\.)\d+/', $str1, $matches);

Update

How's about:

preg_match('/(?<!-|\d|\.)\d+(\.\d+)?/', $str1, $regs);