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[cobol/zh-cn] (#4032)
* translate cobol.html.markdown to chinese version * Update cobol-cn.html.markdown * Update cobol-cn.html.markdown * Update cobol-cn.html.markdown * Update zh-cn/cobol-cn.html.markdown Co-authored-by: 谭九鼎 <109224573@qq.com> --------- Co-authored-by: GOLGO11 <@873200646@qq.com> Co-authored-by: ven <vendethiel@hotmail.fr> Co-authored-by: 谭九鼎 <109224573@qq.com>
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zh-cn/cobol-cn.html.markdown
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---
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language: COBOL
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filename: learn-cn.COB
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contributors:
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- ["Hyphz", "http://github.com/hyphz/"]
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translators:
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- ["GOLGO11", "https://github.com/GOLGO11/"]
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lang: zh-cn
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---
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COBOL是一门面向商业的语言,它从1960年最初设计以来被修订过数次。它被宣称仍然有超过80%的机构在使用它。
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```cobol
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*COBOL. 最好是按照它1985年的标准来编程。
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*用附带GnuCOBOL编译器的OpenCobolIDE 4.7.6来编译。
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*COBOL在老版(COBOL-85)和新版(COBOL-2002以及COBOL-2014)之间有明显的差别。
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*老版COBOL要求编码的前一到六列是空着的(它们被用来存储穿孔卡片的序列号...
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*第七列的一个“*”符号表示注释的开始。
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*在老版COBOL中,一条以*开头的注释最长只能占一行,
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*新版COBOL不需要额外的列来补序列号,并且用“*>" 来注释,允许在行中开始注释
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*老版COBOL也强加了对最大行长度的限制
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*关键字在老版COBOL中必须大写,
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*但在新版COBOL中不区分大小写
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*虽然新版COBOL允许你编写大小写混合的代码
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*但是在大多数情况下编写COBOL代码时全用大写字符
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*大多数专业的COBOL开发者都是这么做的。
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*COBOL语句以句点结尾。
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*COBOL代码被拆成了四个部。
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*各部按顺序,它们是:
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*IDENTIFICATION DIVSION.(标识部)
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*ENVIRONMENT DIVISION.(环境部)
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*DATA DIVISION.(数据部)
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*PROCEDURE DIVISION.(过程部)
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*第一步,我们必须给我们的程序一个ID。
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*Identification division 也能包含其他的值,
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*但它们都只是程序的元数据。Program-id是唯一一个必须给出的值。
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IDENTIFICATION DIVISION.
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PROGRAM-ID. LEARN.
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AUTHOR. JOHN DOE.
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DATE-WRITTEN. 05/02/2020.
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*让我们来声明一些变量。
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*我们要在DATA DIVISION的WORKING-STORAGE节来完成这个事情。
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*每个数据项(又名变量)从一个级别编号开始。
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*然后是数据项的名字,后边再跟着一个picture关键字,
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*来描述这个变量将要包含的数据的类型。
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*几乎所有的COBOL开发者都会把PICTURE简写为PIC。
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*A代表字母,X代表字母和数字,9代表数字。
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*举例:
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01 MYNAME PIC xxxxxxxxxx. *> 十个字符的字符串。
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*但是逐个数那些x会导致错误,
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*所以以上代码可以,并且应该
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*这样重写:
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01 MYNAME PIC X(10).
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*这是几个更多的例子:
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01 AGE PIC 9(3). *> 数字最多三位
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01 LAST_NAME PIC X(10). *> 字符串最多十个字符
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*在COBOL里,一行中多个空格和一个空格的效果是一样的, 所以通常
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*情况下都用多个空格排列代码来便于
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*其他的开发者阅读。
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01 inyear picture s9(7). *> S 使数字为正数.
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*> 括号里意思是重复7次9,
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*> 即六位数字(不是数组)
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*现在让我们来写一点儿代码。这是一个简单的Hello World程序。
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IDENTIFICATION DIVISION.
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PROGRAM-ID. HELLO.
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DATA DIVISION.
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WORKING-STORAGE SECTION.
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01 THE-MESSAGE PIC X(20).
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PROCEDURE DIVSION.
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DISPLAY "STARTING PROGRAM".
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MOVE "HELLO WORLD" TO THE-MESSAGE.
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DISPLAY THE-MESSAGE.
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STOP RUN.
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*以上的代码会输出:
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*STARTING PROGRAM
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*HELLO WORLD
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********用COBOL可以做数学运算***************
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ADD 1 TO AGE GIVING NEW-AGE.
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SUBTRACT 1 FROM COUNT.
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DIVIDE VAR-1 INTO VAR-2 GIVING VAR-3.
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COMPUTE TOTAL-COUNT = COUNT1 PLUS COUNT2.
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*********PERFORM********************
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*PERFORM关键字允许你跳到代码中其他特殊的代码段,
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*当这段特殊的代码被执行完后继续回来执行下面的可执行语句。
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*你必须把PERFORM这个词写完整,不可以缩写它。
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IDENTIFICATION DIVISION.
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PROGRAM-ID. HELLOCOBOL.
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PROCEDURE DIVISION.
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FIRST-PARA.
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DISPLAY 'THIS IS IN FIRST-PARA'.
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PERFORM THIRD-PARA THRU FOURTH-PARA. *>跳过second-para,执行3rd&4th
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*> 之后当third和fourth执行完,
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*> 回到这里继续往下执行直到遇到STOP RUN.
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SECOND-PARA.
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DISPLAY 'THIS IS IN SECOND-PARA'.
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STOP RUN.
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THIRD-PARA.
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DISPLAY 'THIS IS IN THIRD-PARA'.
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FOURTH-PARA.
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DISPLAY 'THIS IS IN FOURTH-PARA'.
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*当你编译执行以上程序时,它会生成以下结果:
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THIS IS IN FIRST-PARA
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THIS IS IN THIRD-PARA
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THIS IS IN FOURTH-PARA
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THIS IS IN SECOND-PARA
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**********用STRING关键字把变量组合到一起************
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*现在是时候学习两个类似的COBOL动词了:string和unstring。.
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*string动词经常被用来连接两个或多个字符串(把它们拼在一起)。
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*没什么特别的,Unstring被用来把一个字符串拆分成两个或多个更小的字符串。
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*当你在程序中使用string或unstring时不要忘记使用”delimited by“,这个很重要。
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IDENTIFICATION DIVISION.
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PROGRAM-ID. LEARNING.
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ENVIRONMENT DIVISION.
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DATA DIVISION.
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WORKING-STORAGE SECTION.
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01 FULL-NAME PIC X(20).
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01 FIRST-NAME PIC X(13) VALUE "BOB GIBBERISH".
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01 LAST-NAME PIC X(5) VALUE "COBB".
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PROCEDURE DIVISION.
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STRING FIRST-NAME DELIMITED BY SPACE
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" "
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LAST-NAME DELIMITED BY SIZE
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INTO FULL-NAME
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END-STRING.
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DISPLAY "THE FULL NAME IS: "FULL-NAME.
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STOP RUN.
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*以上代码将会输出:
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THE FULL NAME IS: BOB COBB
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*让我们来看看为什么是这样。
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*首先,我们在DATA DIVISION声明了所有的变量,
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*包括我们想存储string命令生成的新字符串用到的的变量。
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*这个操作过程在PROCEDURE DIVISION完成。
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*我们从STRING 关键字开始,到END-STRING结束。
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*在它们之间我们列出我们想要组合变量形成更大的主变量的过程。
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*这里,我们组合了FIRST-NAME, 一个空格和LAST-NAME。
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*跟在FIRST-NAME和LAST-NAME后面的DELIMITED BY短语告诉程序我们想要在各自变量上截取字符的规则。
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*DELIMITED BY SPACE告诉程序从最开始截取字符直到遇到一个空格。
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*DELIMITED BY SIZE告诉程序截取字符的完整长度。
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*我们在FIRST-NAME后面使用DELIMITED BY SPACE,字符串中的GIBBERISH部分就被忽略了。
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*为了更清楚,改变代码中的第10行如下:
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STRING FIRST-NAME DELIMITED BY SIZE
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*然后重新执行程序. 这次的输出变成:
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THE FULL NAME IS: BOB GIBBERISH COBB
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```
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## 想了解更多吗?
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* [GnuCOBOL](https://sourceforge.net/projects/open-cobol/)
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