Regular expression to match first and last character

You can do it as follows to check for the first and last characters and then anything in between:

/^[a-z].*[a-z]$/im

DEMO

The below regex will match the strings that start and end with an alpha character.

/^[a-z].*[a-z]$/igm

The a string also starts and ends with an alpha character, right? Then you have to use the below regex.

/^[a-z](.*[a-z])?$/igm

DEMO

Explanation:

^             #  Represents beginning of a line.
[a-z]         #  Alphabetic character.
.*            #  Any character 0 or more times.
[a-z]         #  Alphabetic character.
$             #  End of a line.
i             #  Case-insensitive match.
g             #  Global.
m             #  Multiline