php - Detect First Alphabetic Character -

this easier making out looking determine whether entry user form contains alphabetic character "first" letter only.

example user input:

<input type="text" name="faa_id" size="50" value="<?php echo $_post['faa_id']?>" /> 

example form processing

$faa_id = trim(strtoupper($_request['faa_id']));  if $faa_id = "string character except "n" in first position" {    show url-1; }   else {    show url-2; } 

context: data aircraft registration numbers. enter them in our form without default "n" (i.e. 345fr , not n345fr) not registration number start n.

for example eja345 aircraft callsign shown in place of generic n#, not registration number or c-yehe canadian registration number)

i know how strip first letter if "n" don't know how detect if first letters alphabetic.

i suppose need determine if first character alphabetic character first check see if "n".

if not "n", url 1 if "n" url 2

my code hard code url similar this:

example url-1 http://www.trackmyflight/n

example url-2 http://www.trackmyflight/

try out regex, made looking strings expressions (regularexpressions):

$pattern = '/^[nn].*$/'; 

you can check on regexr.com. type word starts (or doesn't) n , put pattern in box after 'expression'

in php can check http://php.net/preg_match. code should this:

$temp = preg_match($pattern, $faa_id) if($temp === false) {    //if error occurs } else {    if($temp == 0)    {      return url1;    }    else    {      return url2;    } }