strncmp function

I'm new to php and linux. I am trying to replace a password program I used under windows with a mysql based login. I want to compare the first character of the first and last name of the user for a capital letter. My login program passes a user name and password. Below is a start to the program but I'm alittle confused on how to set str1 to check all letters of the alphabet. Can anyone point me to a document or give me an idea on how to do this? I can not use .htaccess do to ISP (host) rules. Access is to a members only sectionof the webpages for my Lions club. -- Russ