COBOL 冒泡排序仅排序 Table 的最后一个元素

Question

我目前正在学习 COBOL，我正在尝试在我的程序中实现冒泡排序算法。虽然我对这门语言还是很陌生，但我所写的内容在语义和句法上对我来说很有意义，但是如果我按顺序输入 5、4、3、2 和 1，我的 post 排序 table 变成 1, 5, 4, 3, 2。有人可以向我解释我哪里出错了吗？

       IDENTIFICATION DIVISION.
         PROGRAM-ID. BubbleSort.

       DATA DIVISION.
         WORKING-STORAGE SECTION.
         01 TVAR PIC 9(4).
         01 CNT PIC 9(1) VALUE 1.
         01 CNT2 PIC 9(1) VALUE 1.
         01 ARR.
            05 ARRELEMENT PIC 9(4) OCCURS 5 TIMES.
         01 TABLELENGTH PIC 9(1) VALUE 5.

       PROCEDURE DIVISION.
         DISPLAY "Enter 5 numbers: ".
         PERFORM INPUT-PARA VARYING CNT FROM 1 BY 1 UNTIL CNT>5.

         DISPLAY "Pre Bubble-Sort: ".
         PERFORM PRINT-PARA VARYING CNT FROM 1 BY 1 UNTIL CNT>5.

         PERFORM BBLSORT-PARA.

         DISPLAY "Post Bubble-Sort: ".
         PERFORM PRINT-PARA VARYING CNT FROM 1 BY 1 UNTIL CNT>5.

         STOP RUN.

         INPUT-PARA.
            ACCEPT ARRELEMENT(CNT).

         PRINT-PARA.
            DISPLAY "Table element: "ARRELEMENT(CNT).

         BBLSORT-PARA.
             INITIALIZE CNT CNT2.
             MOVE 1 TO CNT.
             MOVE 2 TO CNT2.
             PERFORM UNTIL CNT>6
               PERFORM UNTIL CNT2>5
               DISPLAY "IF "ARRELEMENT(CNT) " IS > "ARRELEMENT(CNT2)
                 IF (ARRELEMENT((CNT)) > ARRELEMENT((CNT2)))
                 THEN
                   DISPLAY ARRELEMENT(CNT) " IS > "ARRELEMENT(CNT2)
                    MOVE ARRELEMENT(CNT) TO TVAR
                    MOVE ARRELEMENT(CNT2) TO ARRELEMENT(CNT)
                    MOVE TVAR TO ARRELEMENT(CNT2)
                 END-IF
                 DISPLAY "EXIT IF LOOP"
                 ADD 1 TO CNT2 GIVING CNT2
               END-PERFORM
               ADD 1 TO CNT GIVING CNT
             END-PERFORM.

       END PROGRAM BubbleSort.

Answer 1

免责声明：我不是 COBOL 程序员，但我能够通过对循环的这些更改来完成这项工作。

PERFORM VARYING CNT
           FROM 1 BY 1
          UNTIL CNT > 4

   PERFORM VARYING CNT2
              FROM 1 BY 1
             UNTIL CNT2 + CNT > 5

      COMPUTE
         CNT3 = CNT2 + 1
      END-COMPUTE

      IF (ARRELEMENT((CNT2)) > ARRELEMENT((CNT3)))
         DISPLAY ARRELEMENT(CNT2) " IS > "ARRELEMENT(CNT3)
         MOVE ARRELEMENT(CNT3) TO TVAR
         MOVE ARRELEMENT(CNT2) TO ARRELEMENT(CNT3)
         MOVE TVAR TO ARRELEMENT(CNT2)
      END-IF

      DISPLAY "EXIT IF LOOP"
   END-PERFORM
END-PERFORM.

关键是加了一个CNT3，我用CNT3代表CNT2+1，在内循环之前每次都需要重新发送CNT2为1。然后算法是每次在循环内比较item CNT2和item CNT2+1而不参考CNT。

另外，也不需要每次都在内循环中一直走到数组的末尾。我发现参考 Geeks for Geeks on bubble sort

很有帮助

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