The "+" metacharacter otherwise known as quantifier is used to find the number of times a character or a sequence of characters may occur that is at least one or more times.

For example if we have a pattern "lt+" it matches the string that has the letter "l" followed by "t" atleast once or more than once.So it can give match for "lt", "lttttt", "lturt".

    <?php
    $string = 'laaat';
    if (preg_match('/^(l.+t)/', $string))
     echo "Pattern match";
    else
     echo "Pattern unmatch";    
    ?>

    Pattern match! 

In the above example the pattern is '/^(c.+t)/', specifies the string should start with "c" can have any character by ".", end with one or more occurence of "t".

    #! C:\programfiles\perl\bin\perl
    print "content-type: text/html\n\n";
    if ("lurt" =~ m/lt+/) 
      {
       print "The pattern matched.!\n";
      } 
    else 
      {
       print "The pattern not found!\n";
      }

    The pattern not found!

In the above example's the pattern "lt+" means the string should start with "l" and should have "t" followed at least once or more times, so the string "lurt" gives a unmatch as "l" is not followed by "t".