Basically Useful BASIC

Ascending/Descending Sort

Rick Keck
Overland Park, KS

At some point in time, every computer system user needs the services of a sort program. There has been much work done in the field of "sorting theory" and from this there has come a variety of different sorting methods. Some of these include the bubble sort, shell sort, binary sort, and tag sort. The benefit of this exists in the ability to select a method which is best for sorting data based upon the data's unique characteristics (if any). The factors which influence the decision of which sorting method to use include the following data characteristics: volume, relative order, and storage form (random access or sequential files). In a majority of cases, a simple sorting method will work fine. The standard order of sorting data is to have it sorted from smallest to biggest (ascending order). On occasion, sorting of data may need to be done from biggest to smallest (descending order). The following modified bubble sort routine allows the data to be sorted in either ascending or descending order. Note that the data is handled by character string variables so as to allow alphanumeric data to be sorted.

100 REM****************************
110 REM*                          *
120 REM* ASCENDING / DESCENDING   *
130 REM*                          *
140 REM*     SORT ROUTINE         *
150 REM*                          *
160 REM*  BY RICK KECK 01/81      *
170 REM****************************
180 DIM C$(100)
190 DATA "JOHN", "BILL", "MARY"
200 DATA "CAROLINE", "FRED", "SUE"
210 DATA "JOE"
220 REM* N HOLDS # OF DATA
230 N = 7
240 REM* READ DATA INTO C$
250 FOR J = 1 TO N
260 READ C$(J)
270 NEXT J
280 REM* ASCENDING OR DESCENDING
290 PRINT : PRINT : PRINT
300 PRINT : PRINT "WHAT ORDER DO YOU WISH TO SORT :"
310 PRINT : PRINT " A - ASCENDING (SMALL TO BIG)"
320 PRINT : PRINT " D - DESENDING (BIG TO SMALL)"
330 PRINT : PRINT
340 INPUT A$
350 IF A$<>"A" AND A$<>"D" THEN 340
360 PRINT : PRINT
370 REM**************************            BILL
380 REM*        SORT BEGINS     *            CAROLINE
390 REM**************************            FRED
400 FOR K = 1 TO (N - 1)                     JOE
410 IF A$ = "A" THEN 440                     JOHN
420 IF C$ = (K)> = C$(K + 1) THEN 540        MARY
430 IF A$ = "D" THEN 450                     SUE
440 IF C$(K) < = C$(K + 1) THEN 540
450 FOR J = K TO 1 STEP -1
460 IF A$ = "A" THEN 490
470 IF C$(J)> = C$(J + 1) THEN 540
480 IF A$ = "D" THEN 500
490 IF C$(J) < = C$(J + 1) THEN 540
500 T$ = C$ (J)                              SUE
510 C$(J) = C$(J + 1)                        MARY
520 C$(J + 1) = T$                           JOHN
530 NEXT J                                   JOE
540 NEXT K                                   FRED
550 REM****************************          CAROLINE
560 REM*      SORT ENDS           *          BILL
570 REM****************************
580 FOR L = 1 TO N
590 PRINT C$(L)
600 NEXT L
610 PRINT : PRINT "NORMAL TERMINATION"
620 END