user-0 提问: 请教字符串\0问题。

回复:
user: user-1
content: 请看这个资料 http://blog.csdn.net/libing403

user: user-2
content: 楼上说的很明白了 你预想的是 \0是转义字符，其实是\012   事情就是这么巧

user: user-3
content: 因为有\ 转义字符 \012 是 转义字符,代表十进制的10，就是ASCII码里的换行

user: user-4
content: 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.)

user: user-5
content: 可以参考C++Primer第36页的转义字符 转义字符后面可以紧跟1~3个八进制的数，若八进制数超过3个，则只有3个数字与\构成转义序列。 所以"\0123456"实际包含6个字节，分别为'\012',' 3', '4', '5', '6'和'\0'. 其中，'\012'代表十进制的10，就是个换行符

user: user-6
content: 这样就不会输出了：char x[40] = "\0 123456";

user: user-6
content: ‘\012’ 整体是一个转义字符  \ooo   1到3位八进制数所代表的任意字

user: user-7
content: 看来是转义符的问题。

user: user-8
content: 字符串"\0123456"中"\012"即是8进制的10，\0即八进制，10就是ASCII码的回车符。所以先回车，然后后面输出3456； 另外，字符串结束标志是'\0'，这个是数值0，即数值0就等于'\0'，但是这个一般不在字符串中显示表示，都是自动在字符串后面补一个0（或'\0'）； 以下的代码就是一个显示的给字符串赋值'\0'  #include <stdio.h> #include <string.h>  int main(void) {     char x[40]="\00";     printf("%s\n", x);     printf("%d, %d\n", strlen(x), sizeof(x));     return 0; }