Regular Expressions 101

Save & Share

Sponsor

^[a-z0-9-]$

gmi

^ asserts position at start of a line

Match a single character present in the list below

[a-z0-9-]

+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)

a-z matches a single character in the range between a (index 97) and z (index 122) (case insensitive)

0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case insensitive)

- matches the character - literally (case insensitive)

$ asserts position at the end of a line

Global pattern flags

g modifier: global. All matches (don't return after first match)

m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)

i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

Your regular expression does not match the subject string.Try launching the debugger to find out why.