| cham | Compiled HAM |
| changes | Squeak Changes Data |
| chd | Chart FX Script |
| chef | Chef Source Code |
| chh | Borland C++ Header |
| chi | C To Haskell Interface File |
| chr | Amazon Lumberyard Character Asset Data |
| CryENGINE Character Data |
| chs | Haskell Source With C Hooks |
| cic | Hitachi Ladder Editor Circuit Comment |
| ciq | CONNX InfoNaut Query |
| cjs | CommonJS Script |
| ck | ChucK Source Code |
| ckbx | Cricket Audio XML Bank Description |
| ckg | Kokogut C Output File |
| ckm | Creation Kit Macro |
| cko | Kokogut C Output File |
| ckp | Microsoft SQL Server Checkpoint Data |
| ckx | ChucK Plugin |
| cl | Lisp Source Code |
| OpenCL Kernel |
| cla | Clarion for DOS Source Code |
| class | Gambas V2 Class Data |
| classdiagram | Visual Studio Class Diagram |
| classpath | Eclipse IDE JAVA Project Classpath Data |
| clb | Code Librarian Database |
| clips | Coda Clips Data |
| clj | Clojure Source Code |
| cljc | Clojure Macros Code |
| cljs | ClojureScript Source Code |
| cljx | Clojure Portable Code |
| clog | MPI Parallel Environment CLOG |
| clojure | Clojure Source Code |
| cloud | Crestron SIMPL Cloud Data |
| cls | Visual Basic Class Module |
| clw | Clarion Source Code |
| Visual Studio ClassWizard Data |
| clz | Crestron SIMPL Library Data |
| cma | OCaml Library |
| cmake | CMake Script |
| cmbx | SharpDevelop Combine File |
| cmc | Crestron SIMPL Module |
| cmd | PTC Creo CL Commands Data |
| cmi | OCaml Compiled Interface |
| cml | ProWorx NXT Comment Data |
| cmn | Visual Studio Windows CE Build Settings |
| cmo | OCaml Compiled Bytecode |
| cmt | OCaml CMT Data |
| cmti | OCaml CMT Data |
| cmxa | OCaml Library |
| cntk | Microsoft CNTK Data |
| cnut | Squirrel Compiled Bytecode |
| cob | COBOL Source Code |
| cobol | Micro Focus COBOL Source Code |
| cod | dBase IV Template Source |
| µVision Complete Program Listing Data |
| codaplugin | Coda Plug-in |
| codasite | Coda Site Data |
| cof | Common Object File |
| MPLAB IDE COF File |
| coffee | CoffeeScript JavaScript File |
| cola | Cola Language Source Code |
| comb | Amazon Lumberyard Blend Space Combination Data |
| comp | CodeWarrior Compiler Data |
| com_ | Emu8086 Assembly Source Code |
| conc | Concurnas Source Code |
| container | Eclipse IDE Project Settings Data |
| cord | Visual Studio Cord Data |
| core | Linux Core Dump Data |
| cos | Scarlett Expert System Compiler Query Data |
| Scilab Binary Diagram |
| cosf | Scilab ASCII Diagram |
| counter | NetObjects Fusion Components Bbscomp Message |
| coverage | Visual Studio Code Coverage Data |
| coveragexml | Visual Studio Code Coverage XML Data |
| cox | Click and Create Extension Object |
| cp | CPIde Source Code |
| Xcode C++ Source Code |
| cpb | CPB Data |
| cpd | WebDev Code Style Data |
| cpdsc | CMSIS Pack Project Description |
| cpf | Cab Provisioning Format |
| ProWorx NXT Comment Pointer Data |
| cphd | CloudChan Pre-processed Hypertext Document |
| cpj | CUDA Project |
| cpk | Novell Netware Compiled Server Software Package |
| WDK Driver Test Manager Log |
| cpl | Concordance Desktop Programming Language Script |
| cplist | GNU Make C Property-list Data |
| cplusplus | C++ Source Code |
| cplz | Crestron SIMPL# Pro Library |
| cpp | C++ Source Code |
| Xcode C++ Source Code |
| cpr | Transputer Development System Occam Program Code |
| cpt | Concordance Compiled CPT Script |
| cpy | COBOL Include Data |
| cpz | Crestron SIMPL# Pro Program |
| LoseThos C+ Source Code |
| cr | CRiSP Macro File |
| cr1 | CRBasic Source |
