比如
'\123'
'\n'
等这些，
有没有什么好记的技巧或者好理解的文章呀
刚学C语言，有点懵
首先，你要了解什么是转义，为什么要转义，以及哪些字符要转义，转义字符都长什么样子
如果这些你不知道，那肯定是一脸懵啊
1.并不是所有字符都可见的，比如一个tab键和4个空格看起来一样，但是实际上是不同的字符，字符串结束符、换行符这些也没办法直观的写进代码里，那么就需要引入转义的概念，使这些不可见的字符用可见的形式来表示。同时，\作为转义符，那么想要输入它自身，或者输入双引号之类的，也同样要转义。
2.当转义的是不可见字符或者特殊符号时，\后面跟一个字母，比如\t代表tab，\n代表换行，\0代表结束符,\\代表\本身，\"代表引号本身
3.当转义的内容是ascii码时，\后面跟数字，范围从0-255，也可以是16进制形式\x00-\xFF
4.根据2、3两点，你知道\要与哪些东西结合其实表示的是一个字符，剩下的就是数数了
不建议靠人眼去数字节数，用sizeof()来获取是最准确的
关于C语言所有转义符的信息都在这里
https://en.cppreference.com/w/cpp/language/escape
C++ Character Constants
Character constants are one or more members of the “source character set,” the character set in which a program is written, surrounded by single quotation marks ('). They are used to represent characters in the “execution character set,” the character set on the machine where the program executes.
Microsoft Specific
For Microsoft C++, the source and execution character sets are both ASCII.
END Microsoft Specific
There are three kinds of character constants:
Normal character constants
Multicharacter constants
Wide-character constants
Note Use wide-character constants in place of multicharacter constants to ensure portability.
Character constants are specified as one or more characters enclosed in single quotation marks. For example:
char ch = 'x'; // Specify normal character constant.
int mbch = 'ab'; // Specify system-dependent
// multicharacter constant.
wchar_t wcch = L'ab'; // Specify wide-character constant.
Note that mbch is of type int. If it were declared as type char, the second byte would not be retained. A multicharacter constant has four meaningful characters; specifying more than four generates an error message.
Syntax
character-constant :
'c-char-sequence'
L'c-char-sequence'
c-char-sequence :
c-char
c-char-sequence c-char
c-char :
any member of the source character set except the single quotation mark ('), backslash (), or newline character
escape-sequence
escape-sequence :
simple-escape-sequence
octal-escape-sequence
hexadecimal-escape-sequence
simple-escape-sequence : one of
' " ? \
\a \b \f \n \r \t \v
octal-escape-sequence :
\octal-digit
\octal-digit octal-digit
\octal-digit octal-digit octal-digit
hexadecimal-escape-sequence :
\xhexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit
Microsoft C++ supports normal, multicharacter, and wide-character constants. Use wide-character constants to specify members of the extended execution character set (for example, to support an international application). Normal character constants have type char, multicharacter constants have type int, and wide-character constants have type wchar_t. (The type wchar_t is defined in the standard include files STDDEF.H, STDLIB.H, and STRING.H. The wide-character functions, however, are prototyped only in STDLIB.H.)
The only difference in specification between normal and wide-character constants is that wide-character constants are preceded by the letter L. For example:
char schar = 'x'; // Normal character constant
wchar_t wchar = L'\x81\x19'; // Wide-character constant
Table 1.2 shows reserved or nongraphic characters that are system dependent or not allowed within character constants. These characters should be represented with escape sequences.
Table 1.2 C++ Reserved or Nongraphic Characters
Character ASCII
Representation ASCII
Value Escape Sequence
Newline NL (LF) 10 or 0x0a \n
Horizontal tab HT 9 \t
Vertical tab VT 11 or 0x0b \v
Backspace BS 8 \b
Carriage return CR 13 or 0x0d \r
Formfeed FF 12 or 0x0c \f
Alert BEL 7 \a
Backslash \ 92 or 0x5c \
Question mark ? 63 or 0x3f ?
Single quotation mark ' 39 or 0x27 '
Double quotation mark " 34 or 0x22 "
Octal number ooo — \ooo
Hexadecimal number hhh — \xhhh
Null character NUL 0 \0
If the character following the backslash does not specify a legal escape sequence, the result is implementation defined. In Microsoft C++, the character following the backslash is taken literally, as though the escape were not present, and a level 1 warning (“unrecognized character escape sequence”) is issued.
Octal escape sequences, specified in the form \ooo, consist of a backslash and one, two, or three octal characters. Hexadecimal escape sequences, specified in the form \xhhh, consist of the characters \x followed by a sequence of hexadecimal digits. Unlike octal escape constants, there is no limit on the number of hexadecimal digits in an escape sequence.
Octal escape sequences are terminated by the first character that is not an octal digit, or when three characters are seen. For example:
wchar_t och = L'\076a'; // Sequence terminates at a
char ch = '\233'; // Sequence terminates after 3 characters
Similarly, hexadecimal escape sequences terminate at the first character that is not a hexadecimal digit. Because hexadecimal digits include the letters a through f (and A through F), make sure the escape sequence terminates at the intended digit.
Because the single quotation mark (') encloses character constants, use the escape sequence ' to represent enclosed single quotation marks. The double quotation mark (") can be represented without an escape sequence. The backslash character () is a line-continuation character when placed at the end of a line. If you want a backslash character to appear within a character constant, you must type two backslashes in a row (\). (SeePhases of Translation in the Preprocessor Reference for more information about line continuation.)