Q. 21. Write a program that builds an item-price database on a direct-access file then uses it to find price of an item, given its item number.

Solution.
C      MAIN PROGRAM

COMMON UNT, RECSZ, FNAME

INTEGER UNT, RECSZ
CHARACTER*15 FNAME

UNT = 10
RECSZ = 25
FNAME = ‘PRICE DATABASE’

CALL BLDDAT
CALL USEDAT

STOP
END

SUBROUTINE BLDDAT

COMMON UNT, RECSZ, FNAME

INTEGER UNT, RECSZ
CHARACTER*15 FNAME
CHARACTER STAT*3
INTEGER ITEM
REAL PRICE

STAT = ‘NEW’
CALL FOPEN(STAT)

10     READ ( 5, *, END = 99) ITEM, PRICE
WRITE ( UNT, REC = ITEM) ITEM, PRICE
GO TO 10

99     CLOSE (UNT)
RETURN

END

SUBROUTINE USEDAT

COMMON UNT, RECSZ, FNAME

INTEGER UNT, RECSZ
CHARACTER*15 FNAME
CHARACTER STAT*3
INTEGER ITEM, ITEMNO
REAL PRICE

STAT = ‘OLD’
CALL FOPEN(STAT)

10     PRINT *, ‘ENTER ITEM NUMBER’
READ * , INEMNO

IF (ITEMNO .LE. 0) GO TO 99

READ( UNT, REC = ITEMNO) ITEM, PRICE
PRINT *, ‘PRICE OF ITEM’, ITEM, ‘IS’, PRICE

GO TO 10

99     CLOSE(UNT)
RETURN

END

SUBROUTINE FOPEN(STAT)

CHARACTER*3 STAT

COMMON UNT, RECSZ, FNAME

INTEGER UNT, RECSZ
CHARACTER*15 FNAME

OPEN(UNT,IOSTAT = ISTAT, ERR = 99, FILE = FNAME, STATUS = STAT,
1 ACCESS = ’DIRECT’, FORM = ’UNFORMMATTED’, RECL = RECSZ)
RETURN

99     PRINT*, ‘ERROR IN OPENING’, FNAME, ‘;ERR CODE = ‘ ,ISTAT

STOP
END

Q. 22. Write a program to find out the largest of the given N numbers.

Solution.
DIMENSION X(100)
REAL X, LARGE
INTEGER I, N

C     CAN SELECT FROM MAXIMUM OF 100 NUMBERS

READ *, N
IF (N .GT. 100) THEN
PRINT *, 'TOO MANY NUMBERS'
STOP
ENDIF

C     READ THE NUMBERS

READ *, (X(I), I = 1, N)

C     INITIALIZE

LARGE = X(1)
I = 2

C     PICK THE LARGEST NUMBER.

10 IF (X(I) .GT. LARGE) LARGE = X(I)
I = I + 1
IF (I .LE. N) GOTO 10

C     LARGE HAS THE LARGEST NAUMBER

PRINT *, LARGE
STOP
END