Regex for Validating String Pattern

# Regex for validating a specific string pattern

To validate a string consisting of either (4 digits, a hyphen, 2 digits, a hyphen, 2 digits, an underscore) or (8 digits, an underscore), you can use the following regular expression:

### A possible regex
“`
^(?:\d{4}-\d{2}-\d{2}_|\d{8}_)$
“`

### Regex Breakdown
“`
^ # Matches the start of the string
(?: # Non-capturing group
\d{4}-\d{2}-\d{2}_ # Matches 4 digits, a hyphen, 2 digits, a hyphen, 2 digits, and an underscore
| # OR
\d{8}_ # Matches 8 digits and an underscore
)
$ # Matches the end of the string
“`

Examples of strings that should match this regular expression are:
– `1234-56-78_`
– `98765432_`

### Final notes
This regular expression will match strings that follow the specified pattern of either (4 digits, a hyphen, 2 digits, a hyphen, 2 digits, an underscore) or (8 digits, an underscore). If the string does not match this pattern, it will not be considered a valid match.