seeing the header files in c in linux

Question

i want to know how can one know the functions present in header files in c when running in linux systems

Answer 1

By looking at them. Header files are usually in /usr/include and you can easily browse that folder.

However, some functions might be in different header files depending on the system (linux/bsd/other unixes).

Answer 2

Here: http://www.gnu.org/s/libc/manual/html_node/index.html

If you are writing C on Linux, your standard C library is nearly always the GNU C library. All standard C functions are present in this library, and the link above is to extensive documentation for them.

If you are planning to use libraries other than the standard C library, you should find their documentation as well.

Answer 3

And don't forget, if you know the name of a function you can type man 3 funcname for help on that function, including the name of the header file it appears in. Use the 3 to specify the C Library Function section of the manual. If you forget it and there's a command-line program (section 1) or system call (section 2) with the same name, you'll get that page instead.