regex to match character in specific position
You say you're looking for C, F or E but looking for A in your example, so please include in the brackets any other letters you want to match, but what you're looking for is:
/^.{8}[CFE]/
It should be {8} rather than {9} because the way you had it, it'll match the first 9 characters and then match your letter in position 10.
This way can also solve the problem
/^.{8}A|^.{8}F|^.{8}E/;
you have to use 8 instead of 9 if you want to match the character on the 9th position
Use a character class:
/^.{9}[CFE]/
[CFE]matches one ofC,ForE
Or use the | meta-character (alternation):
/^.{9}(?:C|F|E)/