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

查看:155
本文介绍了文件/组/记录/单元分隔符控制字符及其用法是什么?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

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,但是我真的看不到在哪里使用信息分隔符". (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?他们曾在哪里使用?

What are them? What's the history of them? Where did 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.

这篇关于文件/组/记录/单元分隔符控制字符及其用法是什么?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

查看全文
登录 关闭
扫码关注1秒登录
发送“验证码”获取 | 15天全站免登陆