C

conio.h C Console IO Library
ctype.h C/C++ Ctype Library
curl/curl.h High Level Socket Library
dirent.h Unix Directory Library
math.h C/C++ Mathematics Library
mysql/mysql.h C MySQL API Reference.
stdio.h C Standard IO Library
stdlib.h C Standard Library. (cstdlib in c++)
string.h C/C++ String Library
sys/socket.h Unix Socket Library
winsock2.h Windows Socket Library