!
      PROGRAM P105
!
!
!      CLASS LIST RETRIEVAL PROGRAM
!      FIND SOME STUDENT GRADES
!      USING A HASHING SCHEME WITH THE ID AS THE KEY
!
!      DECLARE ARRAYS FOR FILE
!
      IMPLICIT NONE
      CHARACTER (LEN=25) :: NAMES(100),NAME
      INTEGER :: ID(100),MARKS(100,7),GRADES(7)
!
      INTERFACE
      SUBROUTINE HASH(ID,NR)
      IMPLICIT NONE
      INTEGER ,INTENT(IN OUT) :: ID(:),NR
      END SUBROUTINE HASH
      END INTERFACE
!
      PRINT *, 'This is Program >> P105 = Hashing'
!
!     Tell program where data for  READ is coming from
      OPEN(UNIT=5, FILE='P105.DAT')
! UNIT=5 is the default input
!
!
!===== ZERO OUT ALL ID'S FOR STARTERS
!
L1:   DO J=1,100
         ID(J)=0
      END DO L1
!
!==== READ IN FILE AND STORE IN MAIN MEMORY
!
L2:   DO J=1,100
         READ 15,KD,NAME,GRADES
15       FORMAT(I7,1X,A25,7I3)
         IF(KD == 0) GO TO 101
         Print 15,KD,NAME,GRADES
         CALL HASH(KD,NR)
31       IF(ID(NR) == 0) THEN
!           STORE AWAY THE DATA IN ANY EMPTY SLOT
            ID(NR)=KD
            NAMES(NR)=NAME
L3:         DO K=1,7
               MARKS(NR,K)=GRADES(K)
            END DO L3
!
!===  HERE WE DEAL WITH THE CASE OF A USED SLOT
!     TRY THE NEXT OVER, BUT WATCH FOR END OF THE FILE
!
         ELSE
            NR=NR+1
!              IF AT END - START AT BEGINNING
            IF(NR > 100) NR=1
            GO TO 31
         END IF
      END DO L2
      PRINT 16
16    FORMAT(/'TOO MUCH DATA FOR DEFINED ARRAYS'/  & 'INCREASE ARRAY SIZE AND RERUN'//)
      STOP
!
!==== READ AND PROCESS NAMES REQUESTED
!
101   NREC=J-1
      PRINT 102,NREC
102   FORMAT(/'CLASS LIST PROGRAM - RETRIEVAL BY NAME'/  & I5,' RECORDS ON FILE')
      NREQ=0
L4:   DO J=1,NREC
         READ 202,KID
202      FORMAT(I7)
         IF(KID == 0) THEN
            PRINT 203,NREQ
203         FORMAT(I5,' REQUESTS PROCESSED'/)
            STOP
         ELSE
            NREQ=NREQ+1
            CALL HASH(KID,NR)
231         IF(ID(NR) == 0) THEN
               PRINT 205,KID
205            FORMAT(I9,'   NOT ON FILE - CHECK SPELLING')
            ELSE
               IF(KID == ID(NR)) THEN
                  PRINT 206,KID,NAMES(NR),(MARKS(NR,I),I=1,7)
206               FORMAT(I9,'   ',A25,7I5)
               ELSE
                  NR=NR+1
                  IF(NR > 100) NR=1
                  GO TO 231
               END IF
            END IF
         END IF
      END DO L4
      STOP
      END PROGRAM P105
!
      SUBROUTINE HASH(ID,NR)
      IMPLICIT NONE
      INTEGER ,INTENT(IN OUT) :: ID(:),NR
      INTEGER :: NPRIME=97
      NR=MOD(ID,NPRIME)+1
      RETURN
      END SUBROUTINE HASH