Where could I find the list of all header files in C and C++?
While I am building a library, I am getting an error like 'tree.h not found'.
I suppose this is a standard header file in C and C++. This raised in me the curiosity to know all the header files and their contribution.
Is there a place I can search for?
I am working on Solaris Unix.
The header 'tree.h' is not standard anywhere.
The 15 standard headers in C89 are:
<assert.h> <limits.h> <signal.h> <stdlib.h>
<ctype.h> <locale.h> <stdarg.h> <string.h>
<errno.h> <math.h> <stddef.h> <time.h>
<float.h> <setjmp.h> <stdio.h>
The 3 extra headers introduced in C94* (Amendment 1) are:
<iso646.h> <wchar.h> <wctype.h>
The 6 extra headers in C99 are:
<complex.h> <inttypes.h> <stdint.h> <tgmath.h>
<fenv.h> <stdbool.h>
The 5 extra headers in C2011 (for a total of 29) are:
<stdalign.h> <stdatomic.h> <stdnoreturn.h> <threads.h> <uchar.h>
No extra headers.
The 2 extra headers in C2023 (for a total of 31) are:
<stdbit.h> <stdckdint.h>
Some headers become obsolescent, notably:
<stdalign.h> <stdbool.h> <stdnoreturn.h>
Note that POSIX.1 2008 requires many more headers (82, including all the C99 headers). The list below repeats the standard C (C99) headers. Windows requires a different set of headers, of course.
<aio.h> <libgen.h> <spawn.h> <sys/time.h>
<arpa/inet.h> <limits.h> <stdarg.h> <sys/times.h>
<assert.h> <locale.h> <stdbool.h> <sys/types.h>
<complex.h> <math.h> <stddef.h> <sys/uio.h>
<cpio.h> <monetary.h> <stdint.h> <sys/un.h>
<ctype.h> <mqueue.h> <stdio.h> <sys/utsname.h>
<dirent.h> <ndbm.h> <stdlib.h> <sys/wait.h>
<dlfcn.h> <net/if.h> <string.h> <syslog.h>
<errno.h> <netdb.h> <strings.h> <tar.h>
<fcntl.h> <netinet/in.h> <stropts.h> <termios.h>
<fenv.h> <netinet/tcp.h> <sys/ipc.h> <tgmath.h>
<float.h> <nl_types.h> <sys/mman.h> <time.h>
<fmtmsg.h> <poll.h> <sys/msg.h> <trace.h>
<fnmatch.h> <pthread.h> <sys/resource.h> <ulimit.h>
<ftw.h> <pwd.h> <sys/select.h> <unistd.h>
<glob.h> <regex.h> <sys/sem.h> <utime.h>
<grp.h> <sched.h> <sys/shm.h> <utmpx.h>
<iconv.h> <search.h> <sys/socket.h> <wchar.h>
<inttypes.h> <semaphore.h> <sys/stat.h> <wctype.h>
<iso646.h> <setjmp.h> <sys/statvfs.h> <wordexp.h>
<langinfo.h> <signal.h>
Note, too, that X/Open Curses requires another set of headers. There
was a new version (Release 7) of that specification released in November
2009 (the first update since 1996 — the primary differences are the
loss of official support for termcap and pre-standard C <varargs.h>
header).
<curses.h> <term.h> <uncntrl.h>
POSIX.1 2024 loses a few headers, and gains a few headers compared to POSIX.1 2008. Since it uses the C 2018 standard, it acquires the extra C headers:
<stdalign.h> <stdatomic.h> <stdnoreturn.h> <threads.h> <uchar.h>
It also adds three other headers:
<devctl.h> <endian.h> <libintl.h>
It loses 4 headers that were previously deprecated:
<stropts.h> <trace.h> <ulimit.h> <utime.h>
There are other headers that you might need to use. For example, there
is no mention of <getopt.h> in these lists, but if you are using GNU
Getopt (for long options, for example), you will need and use that
header. It is standard on Linux according to the LSB, Linux Standards
Base. An
older version of the LSB was defined as ISO/IEC 23360:2006 in multiple
parts; as of 2025-03-16, the current version of the LSB is 5.0, which
was released June 3, 2015. There is a section of the document that
defines which headers are included, but there is no convenient table of
the headers in the version I looked at. It is closely aligned with
POSIX, but has extra facilities beyond what POSIX defines.
The standard lists 32 headers specific to C++:
<algorithm> <iomanip> <list> <ostream> <streambuf>
<bitset> <ios> <locale> <queue> <string>
<complex> <iosfwd> <map> <set> <typeinfo>
<deque> <iostream> <memory> <sstream> <utility>
<exception> <istream> <new> <stack> <valarray>
<fstream> <iterator> <numeric> <stdexcept> <vector>
<functional> <limits>
There are also 18 headers corresponding to headers from C (corresponding to C94):
<cassert> <ciso646> <csetjmp> <cstdio> <ctime>
<cctype> <climits> <csignal> <cstdlib> <cwchar>
<cerrno> <clocale> <cstdarg> <cstring> <cwctype>
<cfloat> <cmath> <cstddef>
Intriguingly, Annex D (§D.7) lists a deprecated header, <strstream>,
that is not mentioned earlier in the standard. Including that header
with GCC (g++) 7.2.0 generates a warning:
/opt/gcc/v7.2.0/include/c++/7.2.0/backward/backward_warning.h:32:2:
warning: #warning This file includes at least one deprecated or antiquated
header which may be removed without further notice at a future date.
Please use a non-deprecated interface with equivalent functionality
instead. For a listing of replacement headers and interfaces, consult
the file backward_warning.h. To disable this warning use -Wno-deprecated. [-Wcpp]
The header <strstream> is explicitly listed in the other versions of the standard.
The 53 C++ headers in C++11 are:
<algorithm> <initializer_list> <numeric> <system_error>
<array> <iomanip> <ostream> <thread>
<atomic> <ios> <queue> <tuple>
<bitset> <iosfwd> <random> <type_traits>
<chrono> <iostream> <ratio> <typeindex>
<codecvt> <istream> <regex> <typeinfo>
<complex> <iterator> <scoped_allocator> <unordered_map>
<condition_variable> <limits> <set> <unordered_set>
<deque> <list> <sstream> <utility>
<exception> <locale> <stack> <valarray>
<forward_list> <map> <stdexcept> <vector>
<fstream> <memory> <streambuf>
<functional> <mutex> <string>
<future> <new> <strstream>
The 26 headers related to C (C11) are:
<cassert> <cinttypes> <csignal> <cstdio> <cwchar>
<ccomplex> <ciso646> <cstdalign> <cstdlib> <cwctype>
<cctype> <climits> <cstdarg> <cstring>
<cerrno> <clocale> <cstdbool> <ctgmath>
<cfenv> <cmath> <cstddef> <ctime>
<cfloat> <csetjmp> <cstdint> <cuchar>
Provisional list of headers based on draft standard N3797 found at ISO/IEC JTC1/SC22/WG21 site. The data is from tables 14 and 15 in section 17.6.1.2 Headers, amended as noted below. Since the standard has not been published (as of 2014-09-21), this list is not yet definitive.
The 54 C++ headers in C++14 are:
<algorithm> <initializer_list> <numeric> <strstream>
<array> <iomanip> <ostream> <system_error>
<atomic> <ios> <queue> <thread>
<bitset> <iosfwd> <random> <tuple>
<chrono> <iostream> <ratio> <type_traits>
<codecvt> <istream> <regex> <typeindex>
<complex> <iterator> <scoped_allocator> <typeinfo>
<condition_variable> <limits> <set> <unordered_map>
<deque> <list> <shared_mutex> <unordered_set>
<exception> <locale> <sstream> <utility>
<forward_list> <map> <stack> <valarray>
<fstream> <memory> <stdexcept> <vector>
<functional> <mutex> <streambuf>
<future> <new> <string>
The 26 headers related to C (C11) are unchanged compared with C++11:
<cassert> <cinttypes> <csignal> <cstdio> <cwchar>
<ccomplex> <ciso646> <cstdalign> <cstdlib> <cwctype>
<cctype> <climits> <cstdarg> <cstring>
<cerrno> <clocale> <cstdbool> <ctgmath>
<cfenv> <cmath> <cstddef> <ctime>
<cfloat> <csetjmp> <cstdint> <cuchar>
There is one new header listed for C++14 compared to C++11, namely <shared_mutex>.
NB: The draft lists a number of the headers (<deque>, <istream>,
<stdexcept>, <unordered_set>) twice. Also, 5 headers from C++11 are
not listed in the tables in the draft, namely <exception>,
<iterator>, <ratio>, <scoped_allocator>, and <thread>. Since
§18.8 defines <exception>, §24 defines <iterator>, §20.11 defines
<ratio>, §30 defines <thread>, and §30.4 defines <shared_mutex>,
this is an example of why you should not trust the draft standards as
being the final word — they contain errors.
Provisional list of headers in C++17 based on the draft N4659 dated 2017-03-21. This is a transcription of tables 16 and 17 from section 20.5.1.2 Headers. This is not the final standard; in theory, something could change.
There are 61 C++ headers:
<algorithm> <future> <numeric> <strstream>
<any> <initializer_list> <optional> <system_error>
<array> <iomanip> <ostream> <thread>
<atomic> <ios> <queue> <tuple>
<bitset> <iosfwd> <random> <type_traits>
<chrono> <iostream> <ratio> <typeindex>
<codecvt> <istream> <regex> <typeinfo>
<complex> <iterator> <scoped_allocator> <unordered_map>
<condition_variable> <limits> <set> <unordered_set>
<deque> <list> <shared_mutex> <utility>
<exception> <locale> <sstream> <valarray>
<execution> <map> <stack> <variant>
<filesystem> <memory> <stdexcept> <vector>
<forward_list> <memory_resource> <streambuf>
<fstream> <mutex> <string>
<functional> <new> <string_view>
The new headers compared to C++14 seem to be: <any>, <execution>,
<filesystem>, <memory_resource>, <optional>, <string_view>,
<variant>.
Again, the 26 headers related to C (C11) are unchanged compared with C++11 and C++14:
<cassert> <cinttypes> <csignal> <cstdio> <cwchar>
<ccomplex> <ciso646> <cstdalign> <cstdlib> <cwctype>
<cctype> <climits> <cstdarg> <cstring>
<cerrno> <clocale> <cstdbool> <ctgmath>
<cfenv> <cmath> <cstddef> <ctime>
<cfloat> <csetjmp> <cstdint> <cuchar>
See also What are the new features in C++17?
Note that some of the 'C library' headers are
deprecated in C++17,
specifically <ccomplex>, <cstdalign>, <cstdbool>, <ctgmath> (and
not <ciso646>). The C++ header <codecvt> (added in C++11) is also
deprecated in C++17.
_Provisional list of headers in C++20 based on the draft N4878 dated 2020-12-15. This is a transcription from the "Index of library headers", a new section of the document.
There are 99 C++ headers, including the 'C library' headers:
<algorithm> <csignal> <istream> <span>
<any> <cstdarg> <iterator> <sstream>
<array> <cstddef> <latch> <stack>
<atomic> <cstdint> <limits> <stacktrace>
<barrier> <cstdio> <list> <stdexcept>
<bit> <cstdlib> <locale> <stop_token>
<bitset> <cstring> <map> <streambuf>
<cassert> <ctime> <memory> <string>
<cctype> <cuchar> <memory_resource> <string_view>
<cerrno> <cwchar> <mutex> <strstream>
<cfenv> <cwctype> <new> <syncstream>
<cfloat> <deque> <numbers> <system_error>
<charconv> <exception> <numeric> <thread>
<chrono> <execution> <optional> <tuple>
<cinttypes> <filesystem> <ostream> <type_traits>
<climits> <format> <queue> <typeindex>
<clocale> <forward_list> <random> <typeinfo>
<cmath> <fstream> <ranges> <unordered_map>
<codecvt> <functional> <ratio> <unordered_set>
<compare> <future> <regex> <utility>
<complex> <initializer_list> <scoped_allocator> <valarray>
<concepts> <iomanip> <semaphore> <variant>
<condition_variable> <ios> <set> <vector>
<coroutine> <iosfwd> <shared_mutex> <version>
<csetjmp> <iostream> <source_location>
There are also 27 'C standard .h headers':
<assert.h> <iso646.h> <stdarg.h> <string.h>
<complex.h> <limits.h> <stdatomic.h> <tgmath.h>
<ctype.h> <locale.h> <stdbool.h> <time.h>
<errno.h> <math.h> <stddef.h> <uchar.h>
<fenv.h> <setjmp.h> <stdint.h> <wchar.h>
<float.h> <signal.h> <stdio.h> <wctype.h>
<inttypes.h> <stdalign.h> <stdlib.h>
_Provisional list of headers in C++23 based on the draft N4928 dated 2022-12-18. This is a transcription from the "Index of library headers".
There are 107 C++ headers, including the 'C library' headers:
<algorithm> <cstddef> <istream> <span>
<any> <cstdint> <iterator> <spanstream>
<array> <cstdio> <latch> <sstream>
<atomic> <cstdlib> <limits> <stack>
<barrier> <cstring> <list> <stacktrace>
<bit> <ctime> <locale> <stdexcept>
<bitset> <cuchar> <map> <stdfloat>
<cassert> <cwchar> <mdspan> <stop_token>
<cctype> <cwctype> <memory> <streambuf>
<cerrno> <deque> <memory_resource> <string>
<cfenv> <exception> <mutex> <string_view>
<cfloat> <execution> <new> <strstream>
<charconv> <expected> <numbers> <syncstream>
<chrono> <filesystem> <numeric> <system_error>
<cinttypes> <flat_map> <optional> <thread>
<climits> <flat_set> <ostream> <tuple>
<clocale> <format> <print> <type_traits>
<cmath> <forward_list> <queue> <typeindex>
<codecvt> <fstream> <random> <typeinfo>
<compare> <functional> <ranges> <unordered_map>
<complex> <future> <ratio> <unordered_set>
<concepts> <generator> <regex> <utility>
<condition_variable> <initializer_list> <scoped_allocator> <valarray>
<coroutine> <iomanip> <semaphore> <variant>
<csetjmp> <ios> <set> <vector>
<csignal> <iosfwd> <shared_mutex> <version>
<cstdarg> <iostream> <source_location>
There are also 27 'C standard .h headers':
<assert.h> <iso646.h> <stdarg.h> <string.h>
<complex.h> <limits.h> <stdatomic.h> <tgmath.h>
<ctype.h> <locale.h> <stdbool.h> <time.h>
<errno.h> <math.h> <stddef.h> <uchar.h>
<fenv.h> <setjmp.h> <stdint.h> <wchar.h>
<float.h> <signal.h> <stdio.h> <wctype.h>
<inttypes.h> <stdalign.h> <stdlib.h>
* The 'off by one year' issues in the dates are due to the time it takes to process the standard after it is approved. ANSI approved the original C standard in 1989; ISO approved it in 1990. Amendment 1 was approved in 1994; it was released in 1995.
This answer is available in my SOQ
(Stack Overflow Questions) repository on GitHub as file answer.md in
the
src/so-0202-7991
sub-directory, along with supporting data files such as
c++23-headers.
Try here: http://en.cppreference.com/w/
However, you may also be referring to the header files of your OS. These can be found either on MSDN (Windows) or by man command (POSIX systems). Or another source if you're on another OS.
http://www.cplusplus.com/reference/ lists all the standard C++ headers and the C++ wrappers of C header files.
tree.h is not part of the standard library.
I found this Wikipedia entry on the C standard library which contains, lists of C header files and detailed information on which standard they're part of. That gives you a nice historical perspective and some other, similar details.
Of course that's just C. There's a similar article to be found under "C++ standard library". That also has references to some other libraries which may not be "standard" per se but without which C++ would feel "crippled" to some people used to working with the extensions.
