Question

I am trying to create a RegEx to match a string with the following criterion

• Length 8
• First character must be a letter a-z or A-Z
• The remaining 7 must be numeric 0-9

examples

• a5554444
• B9999999
• c0999999

This is what I have so far

^[0-9]{8}$

What am I missing to check the first character? I tried

^[a-zA-Z][0-9]{8}$

but that’s not working.

Answer 1

I think this is what you want:

^[a-zA-Z][0-9]{7}$

the {…} metacharacter only matches the most previous pattern which in your case is [0-9]. the regex interpretation is as follows:

1. start at the beginning of the string (^)
2. match any character a-z or A-Z ([a-zA-Z]) in the first spot only one time
3. match any character 0-9 starting at the second spot ([0-9])
4. the preceding pattern mentioned in step 3 of [0-9] must exist exactly 7 times ({7})

When you put {8} as per your original question, you’ll assume a string length total of 9: the first character being alphabetic case insensitive and the remaining 8 characters being numeric.