Regular expression searching provides a way to search for advanced combinations of characters. A regular expression included in a search request must be quoted and must begin with ##. Examples:
Apple and "##199[0-9]"
Apple and "##19[0-9]+"
In addition to searching, dtSearch can use regular expressions in File Segmentation and Text Fields rules.
When used in searching, a regular expression must match a single whole word. For example, you could not search for "apple pie" with a regular expression "##app.*ie". The beginning of line and end of line regular expression markers ^ and $ cannot be used in searches.
Special characters in a regular expression are:
|
Regular expression |
Effect |
|
. (period) |
Matches any single character. Example: "sampl." would match "sample" or "samplZ" |
|
\ |
Treat next character literally. Example: in "\$100", the \ indicates that the pattern is "$100", not end-of-line ($) followed by "100" |
|
[abc] |
Brackets indicate a set of characters, one of which must be present. For example, "sampl[ae]" would match "sample" or "sampla", but not "samplx" |
|
[a-z] |
Inside brackets, a dash indicates a range of characters. For example, "[a-z]" matches any single lower-case letter. |
|
[^a-z] |
Indicates any character except the ones in the bracketed range. |
|
.* (period, asterisk) |
An asterisk means "0 or more" of something, so .* would match any string of characters, or nothing |
|
.+ (period, plus) |
A plus means "1 or more" of something, so .+ would match any string of at least one character |
|
[a-z]+ |
Any sequence of one or more lower-case letters. |
dtSearch uses the TR1 implementation of regular expressions, which provides many capabilities beyond what is described above. For more details on TR1 regular expression capabilities, please see this Microsoft article: