! MExample Program 11-2

! Sort a text file containing names.

! there are ten names in test.dat, sort to test5.dat with a new algorithm

!

! The bubble sort algorithm in Example Program 11.2 scans

! through the entire list, each time comparing every contiguous

! pair of elements in the list. Note that the first scan positions

! the largest element at the right end of the list. This means that

! the second scan needs to cover only the first n-2 pairs of elements,

! not n-1 pairs.

!

! Rewrite example program 11.2 to take advantage of this fact.

! Your for statement might be

! for i=1 to scanlimit

! where scanlimit starts at n-1 and is decreased by one after each scan.

DIM List$ (1)

PRINT "Maximum number of names that you plan to sort (10 in test.dat)";

INPUT Capacity

MAT redim List$(1 to Capacity)

LET ArrayFull$ = "false"

LET Count = 0

CALL OpenFile ("Input file name", "old", #1)

CALL OpenFile ("Output file name", "newold", #2)

DO while more #1 and ArrayFull$ = "false"

LET Count = Count + 1

IF Count <= Capacity then

LINE INPUT #1: List$(Count)

ELSE ! Count > Capacity

LET ArrayFull$ = "true"

! The next statement avoids array overflow

! during sorting in the Sort subroutine.

LET Count = Capacity

END IF

LOOP

IF ArrayFull$ = "true" then

PRINT "Only part of the file could";

PRINT " be read because the"

PRINT "maximum number of names";

PRINT " specified was too small."

END IF

CALL Sort (List$, Count)

ERASE #2

FOR Index = 1 to Count

PRINT #2: List$(Index)

NEXT Index

CLOSE #1

CLOSE #2

PRINT "A list of"; Count; "names has been sorted."

END ! of main program

SUB OpenFile (Prompt$, Mode$, #9)

! Prompt for file name and open file.

LET FileOpened$ = "false"

DO

WHEN error in

PRINT Prompt$;

LINE INPUT FileName$

OPEN #9: name FileName$, create Mode$

LET FileOpened$ = "true"

USE

PRINT "Error: "; extext$

PRINT "Check path name and try again."

PRINT

END WHEN

LOOP until FileOpened$ = "true"

END SUB ! OpenFile

SUB Sort (Array$(), N)

! Bubble sort a string array

! in ascending alphabetic order.

DO

LET Sorted$ = "true"

LET scanlimit=n-1

FOR Index = 1 to scanlimit

IF Array$(Index) > Array$(Index + 1) then

LET Temp$ = Array$(Index)

LET Array$(Index) = Array$(Index + 1)

LET Array$(Index + 1) = Temp$

LET Sorted$ = "false"

END IF

LET scanlimit=scanlimit-1

NEXT Index

LOOP until Sorted$ = "true"

END SUB ! Sort