INTRO(3)            UNIX Programmer's Manual             INTRO(3)

NAME
     intro - introduction to subroutines and libraries

SYNOPSIS
     #include <stdio.h>

     #include <math.h>

HP-UX COMPATIBILITY
     Level:    The level given is the level for which the library
               is  available, not the level at which the linkable
               object code appears.   The  supporting  host  will
               contain  appropriate  libraries for HP-UX/RUN ONLY
               and HP-UX/NUCLEUS systems.

     Origin:   System III

DESCRIPTION
     This section describes functions found in various libraries,
     other than those functions that directly invoke HP-UX system
     primitives, which are described in Section 2 of this volume.
     Certain  major  collections are identified by a letter after
     the section number:

     (3C)  These functions, together with those of Section 2  and
           those  marked  (3S), constitute library _l_i_b_c, which is
           automatically loaded by the C  compiler,  _c_c(1).   The
           link  editor _l_d(1) searches this library under the -lc
           option.  Declarations for some of these functions  may
           be  obtained  from  #include  files  indicated  on the
           appropriate pages.
     (3D)  These functions constitute  the  device  I/O  library,
           libdvio.   The link editor searches this library under
           the -ldvio option.  The data structures and  constants
           for  these functions may be obtained from the #include
           file _l_i_b_d_v_i_o._h.
     (3M)  These functions constitute  the  math  library,  _l_i_b_m.
           The  link  editor  searches this library under the -lm
           option.   Declarations  for  these  functions  may  be
           obtained from the #include file <math.h>.
     (3S)  These functions constitute the "standard I/O  package"
           (see  _s_t_d_i_o(3S)).   These functions are in the library
           _l_i_b_c, already mentioned.  Declarations for these func-
           tions   may   be   obtained  from  the  #include  file
           <stdio.h>.
     (3X)  Various specialized libraries.   The  files  in  which
           these libraries are found are given on the appropriate
           pages.

     The descriptions of some functions refer to NULL.   This  is
     the  value  that  is  obtained by casting 0 into a character
     pointer.  The C language guarantees that this value will not
     match that of any legitimate pointer, so many functions that
     return pointers return  it,  for  example,  to  indicate  an
     error.   NULL  is  defined  in  <stdio.h> as 0; the user can
     include his own definition if he is not using <stdio.h>.

FILES
     /lib/libc.a
     /lib/libm.a
     /lib/libdvio.a

SEE ALSO
     ar(1), cc(1), fc(1), ld(1), nm(1), ranlib(1), stdio(3S).

DIAGNOSTICS
     Functions in the math library (3M) may  return  conventional
     values  when  the  function is undefined for the given argu-
     ments or when the value  is  not  representable.   In  these
     cases,  the external variable _e_r_r_n_o (see _e_r_r_n_o(2)) is set to
     the value EDOM or ERANGE.