什么反斜杠“ \”表示实际意思？ [英] What does back slash "\" really mean?

问题描述

我想知道Java的反斜线。计算机或编译器如何看到此反斜杠以及如何将其存储在计算机中？

我读到反斜杠删除了以下字符的特殊含义。但是计算机如何处理这种情况，以及在什么条件下以其他方式处理它？<​​/ p>

例如空字符 \0 在C编程中是字符串的结尾，但是它是一个字符还是两个字符，即反斜杠+零？

反斜杠的目的是指示人类还是指示0-1台计算机？

解决方案

反斜杠 \ 是一个字符，就像字母 A 一样，逗号，和数字 4 。在某些编程语言中，尤其是C及其子代（也许是祖代），在字符串或字符文字内部使用它来转义其他字符。例如，'\a'代表铃铛字符，并且在打印时会从计算机发出蜂鸣声（ printf（％c ，'\a'））。

作为C语言转义字符，在很大程度上是编译器允许的人为构造因此人类可以表达例如钟声。编译后的代码只存储字符-一个值为7的字节。为完全清楚起见，它 not 不会存储 \ a 。

在其他上下文中，反斜杠在运行时对程序意味着某些意义。最著名的例子是正则表达式语法，其中反斜杠转义其他字符，以赋予它们特殊的含义或取消它们可能具有的特殊含义。例如， grep‘\< foo\>’file.txt 将在file.txt中找到带有单词foo的行。在这种情况下，反斜杠确实在运行时出现，并且由程序解释为< 和> 跟着他们。在这种情况下， \< 和 \> 根本不代表字符；它们分别表示一个单词的开头和结尾的零宽度匹配。

I'm wondering about Java's backslash. How does the computer or the compiler see this backslash and how is it stored in computer?

I read that backslash removes the special meaning of the following character. But how does a computer treat this one and in what conditions treat it in some other ways?

For example the null character \0 in C programming, is the end of the string, but is it a single character or two characters, i.e., backslash + zero?

The objective of back slash is to indicate for humans or to indicate for 0-1 computer?

解决方案

The backslash \ is a character, just like the letter A, the comma ,, and the number 4. In some programming languages, notably C and its descendants (and maybe ancestors), it is used inside a string or character literal to escape other characters. For instance, '\a' represents the bell character, and will produce a beep from the computer if you print it (printf("%c", '\a')).

As a C-language escape character, it is largely a human construct allowed by the compiler so humans can express, e.g., the bell character. The compiled code simply stores the character — a byte with the value 7. Just to be absolutely clear, it does not store a \ followed by an a.

Under other contexts, the backslash means something to the program at runtime. The most well-known instance of this is regular expression syntax, in which a backslash escape other characters in order to either give them special meaning or take away a special meaning they might have. For example, grep '\<foo\>' file.txt will locate lines with the word foo in file.txt. In this case the backslashes really are there at runtime, and are interpreted by the program as escapes for the < and > that follow them. In this case, \< and \> don't represent characters at all; they denote a zero-width match against the beginning and end of a word, respectively.

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