| Term | Definition |
| cassert (assert.h) | C Diagnostics Library (header) |
| cctype (ctype.h) | Character handling functions (header) |
| cerrno (errno.h) | C Errors (header) |
| cfloat (float.h) | Characteristics of floating-point types (header) |
| ciso646 (iso646.h) | ISO 646 Alternative operator spellings (header) |
| climits (limits.h) | Sizes of integral types (header) |
| clocale (locale.h) | C localization library (header) |
| cmath (math.h) | C numerics library (header) |
| csetjmp (setjmp.h) | Non local jumps (header) |
| csignal (signal.h) | C library to handle signals (header) |
| cstdarg (stdarg.h) | Variable arguments handling (header) |
| cstddef (stddef.h) | C Standard definitions (header) |
| cstdio (stdio.h) | C library to perform Input/Output operations (header) |
| cstdlib (stdlib.h) | C Standard General Utilities Library (header) |
| cstring (string.h) | C Strings (header) |
| ctime (time.h) | C Time Library (header) |