The filter_id() function returns the ID number of the specified filter.
Returns the ID number of the filter if successful, or NULL if the filter does not exist.
filter_id(filter_name)
| parameter | describe |
|---|---|
| filter_name | Required. Specifies the filter for the ID number to be retrieved. Must be a filter name (not a filter ID name). Please use the filter_list() function to get the names of all supported filters. |
<?phpecho(filter_id("validate_email"));?>The output of the code looks like this:
274