Standard C Library Headers

BSD libc

Superset of the POSIX Standard Library

• <sys/tree.h> – Implementation of Red-black tree and Splay tree
• <sys/queue.h> – Implementations of Linked list, queues, tail queue, etc.
• <fts.h> – Functions to traverse a file hierarchy
• <db.h> – Functions to connect to the Berkeley DB
• <err.h> – Functions to print formatted error messages
• <vis.h> – vis() is used to display non-printable characters in a visual format

C POSIX Library

Superset of the C Standard Library specification for POSIX systems

• <aio.h> - Asynchronous I/O
• <arpa/inet.h> - Functions for manipulating numeric IP addresses (part of Berkeley sockets)
• <assert.h> - Macros assertions
• <complex.h> - Arithmetic with complex numbers
• <cpio.h> - Magic numbers for the cpio archive format
• <dirent.h> - Functions for opening and listing directories
• <dlfcn.h> - Dynamic linking
• <errno.h> - Retrieving Error Number
• <fcntl.h> - File opening, locking, and other file operations
• <fenv.h> - Floating-Point environment
• <float.h> - Floating Types
• <fmtmsg.h> - Message display structures
• <fnmatch.h> - Filename matching
• <ftw.h> - File tree traversal
• <glob.h> - Pathname pattern-matching (globbing)
• <grp.h> - User group information and control
• <iconv.h> - Codeset conversion facility
• <inttypes.h> - Fixed-size integer data-types
• <iso646.h> - Alternative spellings
• <langinfo.h> - Language information constants
• <libgen.h> - Pathname manipulation
• <limits.h> - Implementation-defined constants
• <locale.h> - Category macros
• <math.h> - Mathematical and trigonometric functions
• <monetary.h> - Monetary unit string formatting
• <mqueue.h> - Message queue
• <ndbm.h> - NDBM database operations
• <net/if.h> - List local network interfaces
• <netdb.h> - Translating protocol and hostnames into numeric addresses
• <netinet/in.h> - Internet protocol and address family definitions
• <netinet/tcp.h> - Additional TCP control options
• <nl_types.h> - Localization message catalog functions
• <poll.h> - Asynchronous file descriptor multiplexing
• <pthread.h> - API for creating and manipulating POSIX threads
• <pwd.h> - passwd and user information access and control
• <regex.h> - Regular expression matching
• <sched.h> - Execution scheduling
• <search.h> - Search tables
• <semaphore.h> - POSIX semaphores
• <setjmp.h> - Stack environment declarations
• <signal.h> - Signals
• <spawn.h> - Process spawning
• <stdarg.h> - Handle Variable Argument List
• <stdbool.h> - Boolean type and values
• <stddef.h> - Standard Type Definitions
• <stdint.h> - Integer Types
• <stdio.h> - Standard Buffered I/O
• <stdlib.h> - Standard Library Definitions
• <string.h> - Several String Operations
• <strings.h> - Case-insensitive string comparisons
• <stropts.h> - Stream manipulation and ioctl
• <sys/ipc.h> - Inter-process communication (IPC)
• <sys/mman.h> - Memory management, POSIX Shared Memory, and Memory-mapped files
• <sys/msg.h> - POSIX message queues
• <sys/resource.h> - Resource usage, priorities, and limiting
• <sys/select.h> - Synchronous I/O multiplexing
• <sys/sem.h> - XSI (SysV style) semaphores
• <sys/shm.h> - XSI (SysV style) Shared Memory
• <sys/socket.h> - Main Berkley sockets header
• <sys/stat.h> - File information
• <sys/statvfs.h> - Filesystem information
• <sys/time.h> - Time and date functions and structures
• <sys/times.h> - File access and modification times
• <sys/types.h> - Various data-types
• <sys/uio.h> - Vectored I/O operations
• <sys/un.h> - Unix domain sockets
• <sys/utsname.h> - Operating system information and uname
• <sys/wait.h> - Status of terminated child processes
• <syslog.h> - System error logging
• <tar.h> - Magic numbers for the tar archive format
• <termios.h> - Terminal I/O interfaces
• <tgmath.h> - Type-Generic math macros
• <time.h> - Type-Generic time macros
• <trace.h> - Tracing of runtime behavior
• <ulimit.h> - Resource limiting (DEPRECATED; use <sys/resource.h>)
• <unistd.h> - Various essential POSIX functions and constants
• <utime.h> - Inode access and modification times
• <utmpx.h> - User accounting database functions
• <wchar.h> - Wide-Character handling
• <wctype.h> - Wide-Character classification and mapping utilities
• <wordexp.h> - Word-expansion like the shell would perform

ISO/IEC 9899:1990 (C89, C90)

• <assert.h>
• <ctype.h>
• <errno.h>
• <float.h>
• <limits.h>
• <locale.h>
• <math.h>
• <setjmp.h>
• <signal.h>
• <stdarg.h>
• <stddef.h>
• <stdio.h>
• <stdlib.h>
• <string.h>
• <time.h>

ISO/IEC 9899:1990/Amd.1:1995

• <iso646.h>
• <wchar.h>
• <wctype.h>

ISO/IEC 9899:1999 (C99)

• <complex.h>
• <fenv.h>
• <inttypes.h>
• <stdbool.h>
• <stdint.h>
• <tgmath.h>

ISO/IEC 9899:2011 (C11)

• <stdalign.h>
• <stdatomic.h>
• <stdnoreturn.h>
• <threads.h>
• <uchar.h>

Newlib

• <ctype.h> - Character-type Macro Functions
• <locale.h> - Locale code
• <reent.h> - Re-entrancy support
• <signal.h> - Signal handling
• <stdarg.h> - Macros for variable argument lists (compatible with ANSI C)
• <stdio.h> - I/O
• <stdlib.h> - Standard utility functions
• <string.h> - String-related functions
• <time.h> - Time functions
• <unctrl.h> - Get printable representation of a character
• <varargs.h> - Macros for variable argument lists
• <wchar.h> - Wide-character string-handling functions

X/Open Curses (Release 7)

• <curses.h>
• <term.h>
• <uncntrl.h>

Further Reading

• Standard C Libraries - https://dcjtech.info/topic/standard-c-libraries/
• Linux Libraries (Paths, Files, and Commands) - https://dcjtech.info/topic/linux-libraries-paths-files-and-commands/
• GNU-Toolchain - https://dcjtech.info/topic/gnu-toolchain/
• Cairo Graphics Library - https://dcjtech.info/topic/cairo-graphics-library/
• OpenGL and Other Graphics Libraries - https://dcjtech.info/topic/opengl-and-other-graphics-libraries/
• Library Comparisons - http://www.etalabs.net/compare_libcs.html