php REGEX，尝试从一行中提取两个值（一个可选）

Question

I have a string with many lines and one of those lines is a temperature reading and the method used to take the temperature like so:

Example line 1
temp: 35.20c / 95.36f - axillary
Example line 2

Obviously the temp is "35.20c / 95.36f", and the method is "axillary". The method part is optional. I'm having problems writing a REGEX pattern that will extract both since the method can be optional.

So if i run the pattern in a preg_match_all() on the following string:

temp: 35.20c / 95.36f - axillary
temp: 35.20c / 95.36f
temp: 35.20c / 95.36f - oral

I would expect to get a print similar to this:

Array
(
    [0] => Array
        (
            [0] => temp: 35.20c / 95.36f - axillary
            [1] => temp: 35.20c / 95.36f
            [2] => temp: 35.20c / 95.36f - oral
        )

    [1] => Array
        (
            [0] => 35.20c / 95.36f
            [1] => 35.20c / 95.36f
            [2] => 35.20c / 95.36f
        )

    [2] => Array
        (
            [0] => axillary
            [1] => 
            [2] => oral
        )

I have tried many different patterns, so I'll just post my original (which makes sense to me):

$ptn = "/temp: *(.+)(?: - )?(.+)?/";

Sorry guys I guess I need to add some more details:

• I have no idea what kind of format the temp will be displayed in (35.20c / 95.36f, 35c, 95.3f, etc)
• I basically just need to take everything after the "temp: " and before the hyphen as my temp and everything after that is going to be my method.

Answer 1

Try this one:

<?php

    $lines = "temp: 35.20c / 95.36f - axillary
temp: 35.20c / 95.36f
temp: 35.20c / 95.36f - oral";

  preg_match_all("/^temp:\s+([^-\n]+)( - )?(.*)/m", $lines, $matches);

  print_r($matches);

?>

Answer 2

Ah I think your problem is with (.+) matching everything. Regex patterns are "greedy" and will try and match as much as they possibly can. That pattern matches the rest of the string, leaving nothing for the other groups.

Answer 3

So it looks to me like you want:

/^temp: (\d+\.\d+)c \/ (\d+\.\d+)f(?: - ([^$]+))?$/

The centigrade temp will be in $1, the Fahrenheit version will be in $2, and the method will be in $3. ([^$]+) may not be correct dependiing on what you want to do, since it will capture everything up to the end of the line (like whitespace, if there is any). You could use (?: - ([^$]+?))?\\s*$/ at the end instead, I think that would fix that.

Are the temperatures always in a decimal format? Could they ever just be "0c / 32f"?

---

Edit: Just saw your update. It looks like the greedy .+ is indeed part of the problem, as Rob Agar suggested. You can try this:

/^temp:\s*(\d+(?:\.\d+)?)c\s*\/\s*(\d+(?:\.\d+)?)f(?:\s*-\s*([^$]+?))?\s*$/

That should work even if the method is more than one word. Not sure if that's a possibility, I'm making my best guess at your requirements.

Answer 4

Basically you need a '?' after the capturing group for the method. That indicates that the group may not be there, but the pattern as a whole should still match. What does your pattern look like at the moment?

Answer 5

I might be making some assumptions here but you could try the following

/^temp: ((\d+\.\d+c) / (\d+\.\d+f))( - (\w+))?$/

Due to all the sub-groupings, your matching array will contain more items than in your example but the one's you're after should be in there

Answer 6

$ ptn =“ / temp：（。 ）（\\ s- \\ s）？（。 ）/”;