<assert.h>Contains the assert macro, used to assist with detecting logical errors and other types of bug in debugging versions of a program.
<complex.h>A set of functions for manipulating complex numbers.
<ctype.h> Defines set of functions used to classify characters by their types or to convert between upper and lower case in a way that is independent of the used character set (typically ASCII or one of its extensions, although implementations utilizing EBCDIC are also known).
<errno.h> For testing error codes reported by library functions.
<fenv.h> Defines a set of functions for controlling floating-point environment.
<float.h> Defines macro constants specifying the implementation-specific properties of the floating-point library.
<inttypes.h> Defines exact width integer types.
<iso646.h>Defines several macros that implement alternative ways to express several standard tokens. For programming in ISO 646 variant character sets.
<limits.h> Defines macro constants specifying the implementation-specific properties of the integer types.
<locale.h>Defines localization functions.
<math.h> Defines common mathematical functions.
<setjmp.h>Declares the macros setjmp and longjmp, which are used for non-local exits.
<signal.h>Defines signal handling functions.
<stdalign.h>For querying and specifying the alignment of objects.
<stdarg.h>For accessing a varying number of arguments passed to functions.
<stdatomic.h>For atomic operations on data shared between threads.
<stdbool.h>Defines a boolean data type.
<stddef.h>Defines several useful types and macros.
<stdint.h> Defines exact width integer types.
<stdio.h> Defines core input and output functions
<stdlib.h> Defines numeric conversion functions, pseudo-random numbers generation functions, memory allocation, process control functions
<stdnoreturn.h> For specifying non-returning functions.