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.

[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

);