检查每一行到特定字符的最有效方法是什么

Question

If I pipe an email into a PHP script, and go through each line using fgets , what is the best way to filter out the values from the From: To: and Subject: lines?

I was thinking about exploding each line at : and then checking if ($result[0] === 'To') and so on, but then I'm exploding each line, when I should only be doing that for From , To and Subject

From a Google/SO search I found substr() but you need to specify the number of characters to search, which is different for each value I want.

Answer 1

There is a page out to parse mail headers - They are sharing their regular expressions they are using, so maybe you can simple grab the parts you need:

http://mailheader.mattiasgeniar.be/headers.php

The Regular Expressions suggested for your desired fields are:

From     |^from:(.*)|mi 
To       |^to:(.*)|mi 
Subject  |^subject:(.*)|mi 

Answer 2

you could do something like:

$finds = array('Subject:', 'From:', 'To:');
$founds = array();

$line = fgets(...); // whatever your logic is to get each line

foreach($finds as $key => $find){

    if (substr(trim($line), 0, strlen($find)) == $find){
        $founds[] = array($find, $line);
    }

} 

print_r($founds);  // you can explode (or whatever) the data as needed

this is untested, i just typed it out :)

Answer 3

You could use regular expressions do something like this, for each input $line :

$matches = array();
$params = array();
if (preg_match('/^Subject: (.*)/', $line, $matches) == 1) {
    $params['subject'] = $matches[1];
} elseif (preg_match('/^From: (.*)/', $line, $matches) == 1) {
    $params['from'] = $matches[1];
} elseif (preg_match('/^To: (.*)/', $line, $matches) == 1) {
    $params['to'] = $matches[1];
}