How do I write a regular expression that will match if the 6th character of a string is one of two different letters?

Question

I'm trying to write a validator for an ASP.NET txtbox.

How can I validate so the regular expression will only match if the 6th character is a "C" or a "P"?

Answer 1

^.{5}[CP] will match strings starting with any five characters and then a C or P.

Answer 2

^.{5}[CP] -- the trick is the {}, they match a certain number of characters.

Answer 3

Depending on exactly what you want, you are looking for something like:

^.{5}[CP]

The ^ says to start from the beginning of the string, the . defines any character, the {5} says that the . must match 5 times, then the [CP] says the next character must be part of the character class CP - i.e. either a C or a P.

Answer 4

[a-zA-Z0-9]{5}[CP] will match any five characters or digits and then a C or P.

Answer 5

^.{5}[CP] has a few important pieces:

• ^ = from the beginning
• . = match anything
• {5} = make the previous match the number of times in braces
• [CP] = match any one of the specific items in brackets

so the regex spoken would be something like "from the beginning of the string, match anything five times, then match a 'C' or 'P'"