Question

我对cobol中的计算函数中的四舍五入感到困惑。

声明：

VAR-A      PIC  S9(9)V99 COMP-3.
VAR-B      PIC  S9(9)V9(6) COMP-3.

步骤。

MOVE +12.08 TO VAR-A.
MOVE +6.181657 TO VAR-B.


COMPUTE VAR-A ROUNDED = VAR-A + VAR-B.

VAR-A的结果是18.27还是18.26？ cobol会对计算做什么？它会将VAR-B首先舍入到VAR-A中指定的小数位，还是将cobol添加2个变量然后将它们四舍五入到VAR-A中指定的小数位？

任何帮助将不胜感激。

@NealB，

这个例子怎么样：

声明：

01  VAR-ARRAY  OCCURS 22 TIMES.
    03  VAR-A      PIC  S9(9)V9(6) COMP-3.


01  VAR-B      PIC  S9(9)V99 COMP-3.

假设VAR-A是一个数组，其值如下：

VAR-A(01) =  123.164612
VAR-A(02) =  12.07865
VAR-A(03) =  6.181657
VAR-A(04) =  1.744353
VAR-A(05) =  6.118182
VAR-A(06) =  1.744353
VAR-A(07) =  6.158715
VAR-A(08) =  1.744353
VAR-A(09) =  6.194759
VAR-A(10) =  1.744353
VAR-A(11) =  3.037896
VAR-A(12) =  1.743852
VAR-A(13) =  6.14653
VAR-A(14) =  1.744353
VAR-A(15) =  0.000377
VAR-A(16) =  1.743852
VAR-A(17) =  6.144363
VAR-A(18) =  1.743852
VAR-A(19) =  0.007649
VAR-A(20) =  1.744353
VAR-A(21) =  0.000377
VAR-A(22) =  1.744353

VAR-B的价值是：

VAR-B = 405.25

PROCEDURE：

PERFORM VAR-IDX FROM 1 BY 1 UNTIL VAR-IDX > 22
  COMPUTE VAR-B ROUNDED = VAR-B + VAR-A(VAR-IDX)
END-PERFORM.

为什么计算后得到VAR-B的597.87？

Answer 1

我认为默认的COBOL舍入行为是：最接近于零。

COMPUTE VAR-A ROUNDED = VAR-A + VAR-B

应该导致VAR-A包含18.26

在计算表达式后进行舍入。一个更有趣的例子可能是：

01  VAR-A      PIC  S9(9)V99 COMP-3.               
01  VAR-B      PIC  S9(9)V9(6) COMP-3.             
01  VAR-C      PIC  S9(9)V9(6) COMP-3.             

 MOVE +12.08 TO VAR-A.                         
 MOVE +06.182000 TO VAR-B.                     
 MOVE +00.004000 TO VAR-C.                     
 COMPUTE VAR-A ROUNDED = VAR-A + VAR-B + VAR-C.

结果是18.27。在进行添加之前将VAR-B和VAR-C舍入到2位小数将产生18.26，因为VAR-B轮到6.18并且VAR-C轮到0.00。结果实际上是18.27，因此在评估表达式后进行舍入。

回复已修改的问题

输出效果不错，但这是我使用IBM Enterprise COBOL for z / OS

进行计算的方式

VAR-IDX = 01 VAR-B = +405.25 VAR-A = +123.164612 VAR-B + VAR-A = +528.41
VAR-IDX = 02 VAR-B = +528.41 VAR-A = +012.078650 VAR-B + VAR-A = +540.49
VAR-IDX = 03 VAR-B = +540.49 VAR-A = +006.181657 VAR-B + VAR-A = +546.67
VAR-IDX = 04 VAR-B = +546.67 VAR-A = +001.744353 VAR-B + VAR-A = +548.41
VAR-IDX = 05 VAR-B = +548.41 VAR-A = +006.118182 VAR-B + VAR-A = +554.53
VAR-IDX = 06 VAR-B = +554.53 VAR-A = +001.744353 VAR-B + VAR-A = +556.27
VAR-IDX = 07 VAR-B = +556.27 VAR-A = +006.158715 VAR-B + VAR-A = +562.43
VAR-IDX = 08 VAR-B = +562.43 VAR-A = +001.744353 VAR-B + VAR-A = +564.17
VAR-IDX = 09 VAR-B = +564.17 VAR-A = +006.194759 VAR-B + VAR-A = +570.36
VAR-IDX = 10 VAR-B = +570.36 VAR-A = +001.744353 VAR-B + VAR-A = +572.10
VAR-IDX = 11 VAR-B = +572.10 VAR-A = +003.037896 VAR-B + VAR-A = +575.14
VAR-IDX = 12 VAR-B = +575.14 VAR-A = +001.743852 VAR-B + VAR-A = +576.88
VAR-IDX = 13 VAR-B = +576.88 VAR-A = +006.146530 VAR-B + VAR-A = +583.03
VAR-IDX = 14 VAR-B = +583.03 VAR-A = +001.744353 VAR-B + VAR-A = +584.77
VAR-IDX = 15 VAR-B = +584.77 VAR-A = +000.000377 VAR-B + VAR-A = +584.77
VAR-IDX = 16 VAR-B = +584.77 VAR-A = +001.743852 VAR-B + VAR-A = +586.51
VAR-IDX = 17 VAR-B = +586.51 VAR-A = +006.144363 VAR-B + VAR-A = +592.65
VAR-IDX = 18 VAR-B = +592.65 VAR-A = +001.743852 VAR-B + VAR-A = +594.39
VAR-IDX = 19 VAR-B = +594.39 VAR-A = +000.007649 VAR-B + VAR-A = +594.40
VAR-IDX = 20 VAR-B = +594.40 VAR-A = +001.744353 VAR-B + VAR-A = +596.14
VAR-IDX = 21 VAR-B = +596.14 VAR-A = +000.000377 VAR-B + VAR-A = +596.14
VAR-IDX = 22 VAR-B = +596.14 VAR-A = +001.744353 VAR-B + VAR-A = +597.88
FINAL RESULT = +597.88

Answer 2

IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.

01  VAR_NUM PIC  9(3)V9(02).
01  VAR_RESULT PIC 9(3).


PROCEDURE DIVISION.
    MOVE 256.50 TO VAR_NUM.
    COMPUTE VAR_NUM ROUNDED = VAR_NUM / 100. 
    MULTIPLY 100 BY VAR_NUM
    MOVE VAR_NUM TO VAR_RESULT.
   DISPLAY "Result : " VAR_RESULT.

STOP RUN.

计算舍入为cobol

3 个答案: