Converting a String to Int

Hi, I am sorry this question must seem too easy but I tried searching the php.net site but couldn't find the answer. I need to convert a string to an int. The reason is, I have to extract some numbers from a text file. The text file is in the following format: abtm 2002/06/11 2003/04/04 00:53 3,469 ABBOTSFORD TIMES annw 1999/09/01 2003/04/02 20:15 7,481 ANCASTER NEWS atad 2001/03/13 2002/09/10 19:55 2,227 THE ATHABASCA ADVOCATE IDo you see the part that is bolded ? I need to take it out and subtract that number with an existing integer that is stored in the database. The problem is when I extract this number into a variable let's say $num = 3,469, for some reason $num is actually not an int, because I tried using the is_int() function to check. ANd because of that when I try to subtract this $num with another int variable, I get a number that is wrong because $num isn't an integer, I am guessing it has to do with the comma (3,469) in $num. Can I convert $num=3,469 into an int? If not, can I maybe take out the comma and then convert it to int? Please help THanks Kelvin