CLEAN in Calligra Sheets: Remove Hidden Control Characters

CSV exports, copied identifiers and pasted log messages can contain invisible characters. These can make visually identical values compare differently, disrupt a label, or introduce awkward line breaks when data is concatenated. CLEAN creates a text value with non-printing characters removed, while leaving printable characters in their original order. It does not change the imported source cell, so place the result in another column.

Use CLEAN for presentation-ready strings after inspection; do not destroy line breaks that convey meaning in notes, addresses or multi-line records without checking the result first. If the problem is spaces rather than control characters, distinguish CLEAN from TRIM (whitespace normalization) and SLEEK (removing spaces).

=CLEAN(text)

The official KDE handbook documents one input and a text result. Calligra 26.08.2 registers CLEAN in its text-function module without an alternate name. The pinned func_clean implementation converts the input to a string, tests each Qt character with QChar::isPrint(), and appends printable ones. That is source-code evidence for the intended implementation, not an observation of a particular Linux package or Flatpak build.

Version, platform and locale: This guide targets the official Calligra 26.08.2 source release of October 8, 2026, checked October 11, 2026. The documented primary installation routes are Linux distribution packages and Flatpak; a specific installed package or Windows edition was not tested. One-argument CLEAN needs no argument separator. Composite formulas below use & to join strings. The English KDE handbook uses semicolons between multiple arguments in other functions; if you have a different locale, verify separator and function names in your installed formula editor. The exact return value does not depend on a numeric decimal locale, but coercing non-text inputs may.

1. In A1, enter Raw imported text; in B1, enter Cleaned text.
2. Enter =CHAR(9)&"North"&CHAR(10)&"Dock" in A2; it constructs an ASCII tab, the word North, a line-feed, and Dock. CHAR(code) is documented in the same KDE function handbook, and & joins text in the composite formula; confirm your local formula parser if importing from another application.
3. In B2, enter =CLEAN(A2).
4. Expected B2: NorthDock (the letters remain in order; the control characters are removed). Set the number format to Text if Calligra attempts automatic conversion of other rows.

These are independently reasoned ASCII examples under the documented source-code character test. They are expected results; they have not been native-executed. Displayed spaces in the table may be hard to see, so check using LEN() on the cleaned result if counting matters. For " ABC ", the expected length is 5, not 3.

Suppose A3 contains an imported product name with an embedded tab and you need to flag rows before a data-cleaning review. Enter:

=IF(EXACT(A3;CLEAN(A3));"No non-printing chars found";"Review cleaned value")

If A3 is "AA"&CHAR(9)&"12", the expected result is Review cleaned value because the original and cleaned strings differ. If A3 is "AA 12" (only a printable space), the expected result is No non-printing chars found. The IF and EXACT functions are documented by KDE; this combination has not been native tested.

A second useful check is:

=LEN(A3)-LEN(CLEAN(A3))

For A3 = "A"&CHAR(9)&"B", the expected count of removed characters is 1. It is a character-count difference, not a byte-count, and it does not identify which characters were removed. Preserve A3 until the result has been audited.

• Spaces remain: CLEAN intentionally leaves ordinary spaces; use a separate whitespace-normalization strategy, and confirm that preserving internal spaces matters for identifiers.
• Line breaks disappear: This can be undesirable for addresses or notes. Work on a copy rather than in-place cleaning.
• Output appears unchanged: Not all visually confusing characters are non-printable in the runtime’s Qt character classification. For instance, look-alike hyphens and ordinary spaces are printable.
• Unicode and control-character scope: The pinned source uses Qt’s isPrint() predicate, not a literal list of ASCII codes. The precise Unicode/Qt classification can differ from Excel’s. This guide does not claim a tested map of every code point, embedded NUL, nonbreaking space or variation selector.
• Imported value is not text: The implementation converts its argument to a string. Verify spreadsheet auto-detection, formula separators and numeric formatting if imported dates or numbers appear surprising.
• Error messages or length limits: The handbook does not document an application-independent maximum string length or a precise general error for all input types; no such cap is asserted here.
• Wrong cell: Verify B2 actually contains =CLEAN(A2) rather than a copy of the raw value; the cleaned output remains text.

Microsoft documents Excel CLEAN as originally targeting ASCII codes 0–31 and warns it does not remove certain additional Unicode non-printing codes. By contrast, Calligra’s pinned source filters characters according to Qt QChar::isPrint(). Both should remove common ASCII control characters, but do not assume identical Unicode results across programs or platform builds. LibreOffice documents a CLEAN function that removes non-printing characters and leaves ordinary spaces; Unicode classification and locale should still be tested for consequential imports. Syntax CLEAN(text) is portable for ordinary text examples, not proof of identical edge-case results.

When importing formulas, also check whether Excel function separators (often commas for multi-argument calls) need conversion to the semicolons used in the KDE English documentation. CLEAN itself has just one argument.

The official KDE handbook documents CHAR to create a character from a numeric code, LEN for counting characters, TRIM for spaces and EXACT for comparing text. These links lead to the official KDE documentation.

Primary and compatibility sources (accessed 2026-10-11)

• Official KDE CLEAN reference: purpose, syntax, text argument and sample.
• Pinned Calligra 26.08.2 text-function registry: registration and absence of alias.
• Pinned Calligra func_clean source: text conversion, QChar::isPrint() filter and output.
• KDE Gear 26.08.2 release announcement: release date; not proof of native test success.
• Microsoft Excel CLEAN: ASCII 0–31 and Unicode caveat.
• LibreOffice Calc text functions: CLEAN and related functions.

Validation statement: KDE handbook and exact pinned Calligra source were checked; simple ASCII examples were independently calculated. Native execution: NOT PERFORMED.