strnum.f

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C> @file
C> @author WOOLLEN @date 1994-01-06
      
C> THIS SUBROUTINE DECODES AN INTEGER FROM A CHARACTER STRING.
C>   THE INPUT STRING SHOULD CONTAIN ONLY DIGITS AND (OPTIONAL) TRAILING
C>   BLANKS AND SHOULD NOT CONTAIN ANY SIGN CHARACTERS (E.G. '+', '-')
C>   NOR LEADING BLANKS NOR EMBEDDED BLANKS.
C>
C> PROGRAM HISTORY LOG:
C> 1994-01-06  J. WOOLLEN -- ORIGINAL AUTHOR
C> 2003-11-04  J. ATOR    -- ADDED DOCUMENTATION
C> 2003-11-04  S. BENDER  -- ADDED REMARKS/BUFRLIB ROUTINE
C>                           INTERDEPENDENCIES
C> 2003-11-04  D. KEYSER  -- UNIFIED/PORTABLE FOR WRF; ADDED HISTORY
C>                           DOCUMENTATION
C> 2009-04-21  J. ATOR    -- USE ERRWRT
C>
C> USAGE:    CALL STRNUM (STR, NUM)
C>   INPUT ARGUMENT LIST:
C>     STR      - CHARACTER*(*): STRING CONTAINING ENCODED INTEGER VALUE
C>
C>   OUTPUT ARGUMENT LIST:
C>     NUM      - INTEGER: DECODED VALUE
C>                      -1 = decode was unsuccessful
C>
C> REMARKS:
C>    THIS ROUTINE CALLS:        ERRWRT   STRSUC
C>    THIS ROUTINE IS CALLED BY: JSTNUM   PARUTG   SEQSDX   SNTBFE
C>                               STSEQ
C>                               Normally not called by any application
C>                               programs but it could be.
C>
      SUBROUTINE strnum(STR,NUM)



      CHARACTER*(*) str
      CHARACTER*20  str2

      COMMON /quiet / iprt

C-----------------------------------------------------------------------
C-----------------------------------------------------------------------

      num = 0
      k = 0

C     Note that, in the following call to subroutine STRSUC, the output
C     string STR2 is not used anywhere else in this routine.  In fact,
C     the only reason that subroutine STRSUC is being called here is to
C     determine NUM, which, owing to the fact that the input string STR
C     cannot contain any leading blanks, is equal to the number of
C     digits to be decoded from the beginning of STR.

      CALL strsuc(str,str2,num)
      IF(num.EQ.-1) goto 100

      DO i=1,num
      READ(str(i:i),'(I1)',err=99) j
      IF(j.EQ.0 .AND. str(i:i).NE.'0') goto 99
      k = k*10+j
      ENDDO

      num = k
      goto 100

C     Note that NUM = -1 unambiguously indicates a bad decode since
C     the input string cannot contain sign characters; thus, NUM is
C     always positive if the decode is successful.

99    num = -1
      IF(iprt.GE.0) THEN
      CALL errwrt('++++++++++++++BUFR ARCHIVE LIBRARY+++++++++++++++++')
      CALL errwrt('BUFRLIB: STRNUM - BAD DECODE; RETURN WITH NUM = -1')
      CALL errwrt('++++++++++++++BUFR ARCHIVE LIBRARY+++++++++++++++++')
      CALL errwrt(' ')
      ENDIF

C  EXIT
C  ----

100   RETURN
      END