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icfell(3NCARG)


NAME

   ICFELL - Called to check for existing error conditions and (perhaps) to
   update the current error message and error flag.

SYNOPSIS

   NERR = ICFELL(MESSG,NERRF)

C-BINDING SYNOPSIS

   #include <ncarg/ncargC.h>

   int c_icfell(char *messg, int nerrf)

DESCRIPTION

   ICFELL (which stands for "I Check For Errors on Lower Level") is used
   to check for the occurrence of a recoverable error in a lower-level
   routine and (perhaps) to update the current internal error message and
   error flag.

   The old value of the error flag is returned as the value of the
   function ICFELL. If that value is zero, nothing else has been done. If
   the value of ICFELL is non-zero, the following actions have been taken:

    -  If MESSG is blank, the current error message has not been changed.

    -  If MESSG is non-blank and its length is 6 or less, it should be the
       name of the routine referencing ICFELL; the current error message
       has been altered by prepending first a slash and then MESSG. (Note
       that, if an error occurs several levels deep, the effect of using
       ICFELL in this manner at each level is, effectively, to generate
       traceback information in the error message.)

    -  If MESSG is non-blank and its length is 7 or greater, its value has
       become the new value of the current error message and the previous
       error message has been printed. This is intended for use at the
       beginning of an NCAR Graphics routine to check for an outstanding
       error that the user has not recovered from and to ensure that the
       message for the outstanding error gets printed.

    -  If the expression NERRF has the value zero, the current error flag
       has not been changed.

    -  If the expression NERRF has a non-zero value, the value of the
       current error flag has been made equal to that value.

   An example: Assume that the routine "A" calls the routine "B" and that
   "B" detects an error and calls SETER with error number "32" and error
   message "B - ERROR HAS OCCURRED". If recovery mode is not in effect,
   SETER prints the error message and STOPs; if recovery mode is in
   effect, control returns from "SETER" to "B" and thence to "A". At that
   point, the statement "IF (ICFELL('A',13).NE.0) RETURN" detects the fact
   that an error has occurred in "B" and results in a return from "A" to
   whatever routine called it. It also changes the current error message
   to read 'A/B - ERROR HAS OCCURRED' and changes the error number from
   "32" to "13".

   Another example: Assume that the NCAR Graphics routine "A" is called
   when recovery mode is set and that it detects an error, calls SETER,
   and RETURNs to the user. If the user neglects to check the error state
   and calls the routine "B" next, the statement "IF (ICFELL('B -
   UNCLEARED PRIOR ERROR',1).NE.0) RETURN" ensures that the error message
   from routine "A" will be printed, that it will be replaced by an error
   message referring to the routine "B", and that "B" won't do anything
   else.

   The arguments of ICFELL are as follows:

   MESSG       (an input variable or constant of type CHARACTER) - A
               character string saying what is to be done to the current
               error message (when an error has occurred).  If MESSG is
               blank, no change is to be made in the current error
               message. If the length of MESSG is six characters or fewer,
               a slash is prepended to the current error message and then
               MESSG is prepended to that. If the length of MESSG is seven
               characters or more, MESSG is a complete new error message
               to be substituted for the current one; it should be of the
               form "XXXXXX - TEXT DESCRIBING THE ERROR", where "XXXXXX"
               is the name of the routine in which the error occurred, and
               it should not be more than 113 characters long.

   NERRF       (an input expression of type INTEGER) - A value in the
               range from -999 to +9999. If this value is zero, no change
               is made in the internal error flag; otherwise, it is the
               desired new value of that flag (when an error has
               occurred).

C-BINDING DESCRIPTION

   The C-binding argument descriptions are the same as the FORTRAN
   argument descriptions.

EXAMPLES

   Use the ncargex command to see the following relevant examples: tseter,
   arex02.

ACCESS

   To use ICFELL or c_icfell, load the NCAR Graphics libraries ncarg,
   ncarg_gks, and ncarg_c, preferably in that order.

SEE ALSO

   Online: entsr, eprin, errof, error_handling, fdum, icloem, nerro,
   retsr, semess, seter, ncarg_cbind

COPYRIGHT

   Copyright (C) 1987-2009
   University Corporation for Atmospheric Research
   The use of this Software is governed by a License Agreement.



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