NAME

       gd_get_string — retrieve STRING or SARRAY data from a Dirfile database

SYNOPSIS

       #include <getdata.h>

       size_t gd_get_string(DIRFILE *dirfile, const char *field_code, size_t len, char
              *data_out);

DESCRIPTION

       The gd_get_string() function queries a dirfile(5) database specified by  dirfile  for  the
       string scalar field_code, which should not contain a representation suffix.  The first len
       characters of the string scalar are stored  in  the  user-supplied  buffer  data_out.   If
       field_code refers to a SARRAY field, the first element is returned.

       The  dirfile argument must point to a valid DIRFILE object previously created by a call to
       gd_open(3).

       If len equals zero, or if data_out equals NULL, no data will be copied  to  data_out,  but
       the length of the string scalar will still be returned by gd_get_string().  Otherwise, the
       argument data_out must point to a valid memory location of  sufficient  size  to  hold  at
       least  len  characters.   If the length of the string scalar is greater than len, data_out
       will not be NUL-terminated.

       The gd_get_sarray(3) function provides another way of retrieving STRING data, but  without
       having to know the length of the returned string in advance.  The code:

              size_t len = gd_get_string(dirfile, field_code, 0, NULL);
              char *string = malloc(len);
              gd_get_string(dirfile, field_code, len, string);

       which  ensures  the  whole  string,  including  the  terminating  NUL, is returned, can be
       replaced with, simply:

              const char *string;
              gd_get_sarray(dirfile, field_code, &string);

       with the added benefit of not having manage the memory for the string.

RETURN VALUE

       On success, gd_get_string() returns the actual length  of  the  specified  string  scalar,
       including space for the trailing NUL-character.  A return value greater than len indicates
       that the output string is not NUL-terminated.

       On error, this function returns 0 and stores a negative-valued error code in  the  DIRFILE
       object  which  may be retrieved by a subsequent call to gd_error(3).  Possible error codes
       are:

       GD_E_BAD_CODE
               The field specified by field_code was not found in the database.

       GD_E_BAD_DIRFILE
               An invalid dirfile was supplied.

       GD_E_BAD_FIELD_TYPE
               The supplied field_code referred to a field of type other than STRING or SARRAY.

       GD_E_INTERNAL_ERROR
               An internal error occurred in the library while trying to perform the task.   This
               indicates a bug in the library.  Please report the incident to the maintainer.

       A descriptive error string for the error may be obtained by calling gd_error_string(3).

HISTORY

       The get_string() function appeared in GetData-0.4.0.

       In GetData-0.7.0, this function was renamed to gd_get_string().

SEE ALSO

       gd_get_sarray(3),    gd_error(3),    gd_error_string(3),   gd_open(3),   gd_put_string(3),
       dirfile(5)