php在字符串中的某个单词后直接获取单词

I'm trying to write a script that parses an email and looks for certain strings after certain strings.

For instance, let's say i have the following email body.

$body = "Dear John Doe, your information is below
Check in date: 07/23/2012
Check out date: 07/26/2012

Alternate Check in date: 07/27/2012
Alternate Check out date: 07/29/2012";

I want to grab the 'word' directly after the first instance of "Check in date:", which would be "07/23/2012". The 'word' being the next set of characters with spaces around it. I included the 'alternate' parts because some emails will have a text version and an html version.

I think i need to use a combo of strpos(), substr(), and explode() but i'm not sure how. Any suggestions?

Exactly what regular expressions are good for:

preg_match('/(?<=Check in date: )\S+/i', $string, $match);
echo $match[0];

http://www.regular-expressions.info

This is a good use-case for regexes:

if (preg_match('#^Check in date: ([^\s]+)#m', $body, $match)) {
    $result = $match[1];
}

Try it here: http://codepad.viper-7.com/W4UW4P