文件/组/记录/单元分隔符控制字符及其用法是什么? [英] What are the file/group/record/unit separator control characters and their usage?

问题描述

Unicode从ASCII定义了几个控制字符. http://www.unicode.org/charts/PDF/U0000.pdf

Unicode defines several control characters from ASCII. http://www.unicode.org/charts/PDF/U0000.pdf

我看到许多控制字符被广泛使用，但我真的看不到信息分隔符"在哪里.被使用.(U + 001C〜U + 001F)

I see many control characters are widely used but I really don't see where "information separators" are used. (U+001C~U+001F)

它们是什么?他们的历史是什么?他们是用来干什么的?

What are they? What's their history? What were they used for?

推荐答案

Lammert Bies解释了它们的用法和背后的历史.

Lammert Bies explains both their usage and the history behind.

28 – FS –文件分隔符文件分隔符FS是一个有趣的控件代码，因为它使我们对计算机技术的方式在六十年代组织的.我们现在用于随机存取RAM之类的媒体和磁盘，但当使用ASCII时定义了标准，大多数数据是序列.我不仅在谈论串行通讯，还要讲连续存储，如打孔卡，纸张磁带和磁带.在这样的情况显然是有效的只需一个控制代码即可发出信号两个文件的分离.FS是为此目的而定义的.

28 – FS – File separator The file separator FS is an interesting control code, as it gives us insight in the way that computer technology was organized in the sixties. We are now used to random access media like RAM and magnetic disks, but when the ASCII standard was defined, most data was serial. I am not only talking about serial communications, but also about serial storage like punch cards, paper tape and magnetic tapes. In such a situation it is clearly efficient to have a single control code to signal the separation of two files. The FS was defined for this purpose.

29 – GS –组分隔符数据存储是其中之一一些控制的主要原因代码以获取ASCII定义.数据库大部分时间是在设置中与表，包含记录.全部一个表中的记录具有相同的类型，但记录不同的表可以不同.组分隔符GS定义为将表中的表分开串行数据存储系统.注意那个词表并没有被使用瞬间，ASCII人称它为一个小组.

29 – GS – Group separator Data storage was one of the main reasons for some control codes to get in the ASCII definition. Databases are most of the time setup with tables, containing records. All records in one table have the same type, but records of different tables can be different. The group separator GS is defined to separate tables in a serial data storage system. Note that the word table wasn't used at that moment and the ASCII people called it a group.

30 – RS –记录分隔符在组(或表)中的记录与RS或记录分开分隔符.

30 – RS – Record separator Within a group (or table) the records are separated with RS or record separator.

31 –美国–单位分隔符要存储的最小数据项在数据库中被称为单位ASCII定义.我们会称他们为现在.单位分隔符将这些字段按序列分开数据存储环境.最新数据库实现要求大多数类型的字段都有固定值长度.记录中有足够的空间是分配存储最大每个字段的可能成员，即使在大多数情况下，这不是必需的.这会占用大量空间很多情况.美国控制代码允许所有字段都具有变量长度.如果数据存储空间为有限(例如60年代)保留宝贵空间的好方法.另一方面是串行存储效率远低于桌子驱动的RAM和磁盘实现现代.我无法想象现代SQL数据库的情况使用存储在纸上的数据运行磁带或磁性卷轴...

31 – US – Unit separator The smallest data items to be stored in a database are called units in the ASCII definition. We would call them field now. The unit separator separates these fields in a serial data storage environment. Most current database implementations require that fields of most types have a fixed length. Enough space in the record is allocated to store the largest possible member of each field, even if this is not necessary in most cases. This costs a large amount of space in many situations. The US control code allows all fields to have a variable length. If data storage space is limited—as in the sixties—this is a good way to preserve valuable space. On the other hand is serial storage far less efficient than the table driven RAM and disk implementations of modern times. I can't imagine a situation where modern SQL databases are run with the data stored on paper tape or magnetic reels...

单位分隔符可以提供与CSV文件中的逗号或制表符分隔文件中的制表符基本相同的目的.

A Unit separator could provide essentially the same purpose as a comma in a CSV file or a tab in a tab-delimited file.

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