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FORTRAN Bubble Sort Speghetti Code
[^] CSc 404 Documentation And Examples
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sort.f
This program is written the style of the earliest FORTRAN. It reads up to 15 integers, stopping either when it gets 15, or when -1 is input. It then sorts them and prints the result. The read loop is created by the GOTO 10 instruction, and exits by jumping either to line 40 (if a -1 was input) or 70 after the 15th number is entered.

The inner sort loop extends from line 50 to the GOTO 50, and the outer from 70 to GOTO 70. The 90 line leaves the inner loop, and the 100 line leaves the outer one.

Printing is accomplished with a DO loop, the most advanced control construct available.

      DIMENSION NUMS(15)
C
C READ IN THE ARRAY, UNTIL -1 OR 15 NUMBERS READ.  
C LEAVE THE NUMBER READ IN N.
      N = 1
 10   READ 15, IN
 15   FORMAT(I3)
      IF(IN + 1) 20,40,20
 20   NUMS(N) = IN
      IF(N - 15) 25,70,70
 25   N = N + 1
      GOTO 10
C
C SORT THE ARRAY USING BUBBLE SORT.
 40   N = N - 1
 70   ISCAN = 1
      IOK = 1
      ISTOP = N
      IF(ISTART - ISTOP) 50, 110, 110
 50   IF(NUMS(ISCAN) - NUMS(ISCAN+1)) 90,90,60
C
C SWAP
 60   J = NUMS(ISCAN)
      NUMS(ISCAN) = NUMS(ISCAN+1)
      NUMS(ISCAN+1) = J
      IOK = 0
C
C TIME TO ISTART OVER?
 90   IF(ISCAN - (ISTOP - 1)) 80,100,100
C
C NEXT PAIR
 80   ISCAN = ISCAN + 1
      GOTO 50
C
C NEXT ISCAN
 100  IF(IOK) 105,105,110
 105  ISTOP = ISTOP - 1
      GOTO 70
C
C PRINT
 110  DO 120 I=1, N
 120  PRINT 130, NUMS(I)
 130  FORMAT(I10)
      STOP
      END