REGEXREPLACE Function in Gnumeric: Syntax, Examples and Troubleshooting

=REGEXREPLACE(text, pattern, replacement, [occurrence], [case_insensitive])

The inspected source returns unchanged input if no match, or if the requested nonzero occurrence doesn’t exist. Invalid regular expressions and invalid replacements can produce a #VALUE!-type error. These error paths are source-inspected, not native-tested.

1. Add headers Original to A1 and Masked to B1.
2. Copy the A values below into A2:A5. They are fictional strings.
3. Enter =REGEXREPLACE(A2,"[0-9]+","*****") in B2 and fill through B5.

Why: [0-9]+ matches each consecutive run of ASCII digits. Since occurrence defaults to zero, each run is replaced by five asterisks. This is a text demonstration, not comprehensive privacy-preserving anonymization.

To replace only the second numeric run:

=REGEXREPLACE("A-123 B-456","[0-9]+","X",2)

Expected: A-123 B-X. Using -1 instead of 2 also replaces the last run and gives A-123 B-X. Using 9 leaves the original unchanged because that occurrence does not exist.

A capturing-group rearrangement:

=REGEXREPLACE("2026-10-11","^([0-9]{4})-([0-9]{2})-([0-9]{2})$","$2/$3/$1")

Expected: 10/11/2026 as text, not as a true date serial; this is not calendar-date validation. For case-insensitive replacement:

=REGEXREPLACE("CAT cat","cat","dog",0,TRUE)

Expected: dog dog.

• Too many matches replaced: The default occurrence=0 means all matches. Specify 1, 2 or -1 to narrow it.
• Text unchanged unexpectedly: The pattern may not match, or the specified occurrence may be out of range. Verify the source text and case settings.
• . matches too broadly: Use [.] for a literal period. Use ^/$ if the entire string must match.
• Regex errors: Badly balanced ( or [ can fail compilation and return #VALUE!-type error in the inspected source. Complex backreferences should be tested with simple synthetic examples first.
• Identifiers with leading zeros: Import ID fields as text so 0012 stays four characters.
• Data privacy: Replacing number runs does not guarantee all identifiers are removed; check the remaining text and relevant policies.

Microsoft 365 Excel documents a similarly ordered five-argument REGEXREPLACE, including negative occurrence selection. Excel calls its last flag case_sensitivity; Gnumeric calls it case_insensitive. Engine differences and importer/exporter formula translations need native checking. For a known literal substring, use the simpler SUBSTITUTE instead of regex.

These examples target Gnumeric 1.12.62, whose official release announcement lists this function as newly introduced. Its registered name and argument information were checked against the GNOME source-code function definitions and string-function registry (GitHub’s GNOME mirror, pinned to commit 5d556a736fa3). The project’s release-specific source archive was enumerated in the pre-existing independent catalogue audit, but its bytes were not downloaded again in this batch. The public Gnumeric function index lags the audited release registry; absence from that list does not prove absence from 1.12.62. This guide does not promise availability in earlier versions or every downstream installation with different plugins.

Formulas use an English-language, comma-separated argument style with decimal dots where necessary. Regional settings can change the displayed argument separator and translated user interface; if pasting fails, insert the function through Gnumeric’s own function editor. Regex patterns are strings, so put double quotes around literal patterns in a formula; cell references such as A2 do not take quotes. A regex searches for a match within a string unless you explicitly anchor it with ^ and $. The implementation calls GLib GRegex; pattern portability with other spreadsheet regex engines is not guaranteed.

• Gnumeric — function documentation
• GNOME source-code function definitions
• string-function registry
• Gnumeric function index

Verification status: Official documentation checked; example outcomes were independently reasoned or arithmetically checked where applicable. Not executed in Gnumeric.

• No genuine Gnumeric screenshots are included; this guide does not use mock application images.