COBOL中数字和字符串的布尔值

Question

大多数编程语言将任何非零数字和非空字符串识别为true。我想知道COBOL是否也一样？

Example1：（9 && 2）被识别（true && true），因此返回trueExample2：（“” &&“ Hello”）被识别（false && true），因此返回false

谢谢！

Answer 1

通过Google搜索：

布尔数据项COBOL不直接支持逻辑/布尔变量但是，级别88用于定义条件名称，具有相同的效果。

Answer 2

大多数编程语言将任何非零数字和非空字符串识别为true。我想知道COBOL是否也一样？

没有这样的使用会导致语法错误。

   procedure division.
       if 9 and 2
           display "true"
       else
           display "false"
       end-if
       if "" and "Hello"
           display "true"
       else
           display "false"
       end-if
       stop run
       .

---

     1 procedure division.
     2     if 9 and 2
* 315-S************                                                    (   0)**
**    Invalid conditional expression
     3         display "true"
     4     else
* 562-S********                                                        (   1)**
**    An "ELSE" phrase did not have a matching IF and was discarded.
     5         display "false"
     6     end-if
* 564-S**********                                                      (   1)**
**    A scope-delimiter did not have a matching verb and was discarded.
     7     if "" and "Hello"
*1010-E*********                                                       (   1)**
**    Nonnumeric literal has length of zero. One SPACE assumed.
* 315-S*************                                                   (   1)**
**    Invalid conditional expression
     8         display "true"
     9     else
* 562-S********                                                        (   1)**
**    An "ELSE" phrase did not have a matching IF and was discarded.
    10         display "false"
    11     end-if
* 564-S**********                                                      (   1)**
**    A scope-delimiter did not have a matching verb and was discarded.
    12     stop run
    13     .

Answer 3

Cobol 没有与其他语言一样具有布尔值，取而代之的是88个级别。88个级别可以应用于其他类型。它们涵盖布尔值和枚举其他语言。

基本布尔值88级

您可以做

    05 Filler              pix x value 'N'.
       88 end-of-file value 'Y'.
       88 more-date-in-file value 'N'


    perform until   end-of-file
        ...

        read Transaction-File
         at end set end-of-file    to True
   end-perform

基本枚举88级

  03 Transaction-Code                pic s9(4) comp-3.
     88 Purchase-Transaction value    1000, 1001, 1005 thru 1009.
     88 Sales-Transaction    value    2000, 2010, 2020.
     88 Price-Adjustment     value    2050.
     88 Transfer-Transaction value    1050.



  evaluate true
     when Purchase-Transaction
       ...
     when Sales-Transaction    
       ...

摘要

88级提供基本的布尔变量（但不提供布尔代数）。他们也允许您记录变量可以采用的可能值+含义