Help with simple regex

[smith.james0]

I have the following string 

ds WSW 16km/h. Humidity will be 97% with….

 

I would like to get the 16km/h to replace it. This is my first time writing regex and after a bit of reading I thought this might work, (\S+)km/h\s but it doesn't 

 

Can anyone help?

 

James

[.josh]

preg_match('~\b\d+km/h\b~',$string,$match);

[Psycho]

What are you trying to replace it with? Do you just want to replace the km/h or do you need to first get the number to convert it to a different unit? If you need to do the latter, you will need to do a preg_match() to get the number and then a preg_replace to replace the number and the unit measurement.

$subject = 'ds WSW 16km/h. Humidity will be 97% with . . .';

//Check if string contains ##km/h
if(preg_match("#(\d*)km/h#is", $subject, $match))
{
    //Extract kilos
    $kmUnits = $match[1];
    //Convert to miles
    $mileUnits = round($kmUnits * .6214);
    //Replace kilo reference with miles
    $subject = preg_replace("#\d*km/h#is", "{$mileUnits}mph", $subject);
}

echo $subject;

Output: ds WSW 10mph. Humidity will be 97% with . . .

 

Note: This only works if the subject has one such reference. If there can be multiple such references in the same text, then you would need to modify the above.

Edited December 27, 2013 by Psycho

[smith.james0]

hmmm my expression was really wrong    thanks Psycho for the extra bit of code, could you explain how I would go about changing multiple references? 

 

James

[.josh]

$subject = 'ds WSW 16km/h. Humidity will be 97% with 28km/h. . .';

 

$subject = preg_replace_callback(

  '~\b(\d+)km/h\b~i',

  function($m){return round($m[1]*.6214).'mph';},

  $subject

);