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`.cxx`

2 claimants 1 primary 1 secondary unambiguous primary

SWH popularity

From the SWH-MSR-ARV dataset (Desmazières, Di Cosmo, Lorentz, MSR 2025; file nb_extensions_alphanum.csv) — one row per (ext, year) in the full SWH archive. Case-aggregated. citation.

6.9M

total occurrences

1.0M

since 2019 (15.0%)

1970–2023

years active

Case variants in archive: .cxx (6.9M), .CXX (11.7K), .Cxx (128), .cXX (6) — aggregated above.

Attribution status

This extension is attributed to C++ as primary by 1 authoritative claim.

Authoritative sources: △ Linguist · secondary △ Pygments · secondary ✓ Wikidata · Q2407 ✗ Wikipedia · no claim

Disagree or have a correction? Open a labelling issue.

Claimants (4)

Languages that list .cxx among their extensions. Strength reflects whether the upstream source treated it as their primary extension.

Language	Source	Strength
C++	wikidata	primary
C++	linguist	secondary
C++	pygments	secondary
cpp	pygments	secondary

Wikidata says… (1)

File formats, image formats, audio codecs and other non-PL entities that claim .cxx on Wikidata (property P1195) or in the Wikipedia infobox. Source: data/derived/external_extension_index.csv. Click Use as new PL on any row to open the Add-PL form pre-filled with that entry's name, Wikipedia/Wikidata URL, and this extension — one submission creates the PL + claim.

Right entry isn't listed? Add manually ↗

Format	Class (Wikidata `P31`)	Suggested label	MIME	Notes	Action
C++ source code file Q111417227 file format	file format	—	`—`	—	Use as new PL ↗

SWH-mined examples (1)

Real archived programs with this extension, byte-verified against the SWH archive. Useful for deciding what this extension actually is when the attribution is uncertain.

rtkXRadImageIO.cxx · 5883 B · seen 1781× in SWH

predicted: unclassified via fallback

swh:1:cnt:fb02952016ed37ce421de70ea8dd312694974167;origin=https://github.com/vfonov/vv;anchor=swh:1:rev:942db0e6f00e876ac6fbea41076db2ff703010a5;path=/common/rtkXRadImageIO.cxx

Open in SWH · Raw bytes