$string = file_get_contents("example.txt"); // Load text file contents
   $matches = array(); //create array
   $pattern = '/[A-Za-z0-9_-]+@[A-Za-z0-9_-]+.([A-Za-z0-9_-][A-Za-z0-9_]+)/'; //regex for pattern of e-mail address
   preg_match($pattern, $string, $matches); //find matching pattern

$string = file_get_contents("example.txt"); // Load text file contents

// don't need to preassign $matches, it's created dynamically

// this regex handles more email address formats like a+b@google.com.sg, and the i makes it case insensitive
$pattern = '/[a-z0-9_-+]+@[a-z0-9-]+.([a-z]{2,3})(?:.[a-z]{2})?/i';

// preg_match_all returns an associative array
preg_match_all($pattern, $string, $matches);

// the data you want is in $matches[0], dump it with var_export() to see it
var_export($matches[0]);

array (
  0 => 'test1+2@gmail.com',
  1 => 'test-2@yahoo.co.jp',
  2 => 'test@test.com',
  3 => 'test@test.co.uk',
  4 => 'test@google.com.sg',
)

/[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,4}/

$sourceeee= 'Here are examplr mymail@yahoo.com and my-e.mail@goog.com or something more';

preg_match_all('/[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,4}/i', $sourceeee, $found_mails);

<?
$url="http://example.com/";
$text=file_get_contents($url);
$res = preg_match_all(
"/[a-z0-9]+[_a-z0-9.-]*[a-z0-9]+@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,4})/i",
$text,
$matches
);
if ($res) {
foreach(array_unique($matches[0]) as $email) {
echo $email . "<br />";
}
}
else {
echo "No emails found.";
}
?>

<?php
$content = "Hi my name is Joe, I can be contacted at joe@mysite.com.";
preg_match("/[_a-z0-9-]+(.[_a-z0-9-]+)*@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,3})/i", $content, $matches);
print $matches[0];
?>

<?php
function extract_email_addresses($str){
    $emails = array();
    $str = strip_tags( $str );
    $str = preg_replace('/s+/', ' ', $str);
    $str = preg_replace("/[nr]/", "", $str);
    $remove_chars = array (',', "<", ">", ";", "'", ". ");
    $str = str_replace( $remove_chars, ' ', $str );
    $parts = explode(' ', $str);
    if(count($parts) > 0){
        foreach($parts as $part){
            $part = trim($part);
            if( $part != '' ) {
                if( filter_var($part, FILTER_VALIDATE_EMAIL) !== false){
                    $emails[] = $part;
                }
            }
        }
    }
    if(count($emails) > 0){
        return $emails;
    }
    else{
        return null;
    }
}

$string = "Guys, please help me to extract valid sam-ple.1990@gmail.co.uk email addresses from some text content using php
example , i have below text content in mysql database ' Life is more beautiful, and i like to explore lot please email me to sample@gmail.com. Learn new things every day. 'from the above text content i want to extract email address 'sample-x@gmail.com' using php regular expressions or other method.";

$matches = extract_email_addresses( $string );
print_r($matches);

?>