C++ “\0”是什么意思？
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What does '\0' mean?
提问by halostack
I can't understand what the '\0' in the two different place mean in the following code:
我无法理解以下代码中两个不同位置的 '\0' 是什么意思：
string x = "hhhdef\n";
cout << x << endl;
x[3]='char *c =”Hello”; // it is actually Hello##代码##
char c[] = {‘Y','o','##代码##′};
';
cout << x << endl;
cout<<"hhh##代码##defef\n"<<endl;
Result:
结果：
hhhdef
hhhef
hhh
高清
哈哈
呵呵
Can anyone give me some pointers?
谁能给我一些指点？
回答by Matteo Italia
C++ std::strings are "counted" strings - i.e., their length is stored as an integer, and they can contain any character. When you replace the third character with a \0nothing special happens - it's printed as if it was any other character (in particular, your console simply ignores it).
C++ std::strings 是“计数”字符串——即，它们的长度存储为整数，并且它们可以包含任何字符。当您将第三个字符替换为\0没有什么特别之处时 - 它会像打印任何其他字符一样打印（特别是，您的控制台只是忽略它）。
In the last line, instead, you are printing a C string, whose end is determined by the first \0that is found. In such a case, coutgoes on printing characters until it finds a \0, which, in your case, is after the third h.
相反，在最后一行中，您正在打印一个 C 字符串，其结尾由\0找到的第一个字符串确定。在这种情况下，cout继续打印字符，直到找到 a \0，在您的情况下，它在第三个之后h。
回答by Konrad Rudolph
C++ has two string types:
C++ 有两种字符串类型：
The built-in C-style null-terminated strings which are really just byte arrays and the C++ standard library std::stringclass which is notnull terminated.
内置的 C 风格空终止字符串实际上只是字节数组和非空终止的 C++ 标准库std::string类。
Printing a null-terminated string prints everything up until the first null character. Printing a std::stringprints the whole string, regardless of null characters in its middle.
打印以空字符结尾的字符串会打印所有内容，直到第一个空字符为止。打印 a 会std::string打印整个字符串，而不管其中间的空字符如何。
回答by cmc
\0is the NULL character, you can find it in your ASCII table, it has the value 0.
\0是 NULL 字符，您可以在您的 中找到它ASCII table，它的值为 0。
It is used to determinate the end of C-style strings.
它用于确定 C 样式字符串的结尾。
However, C++ class std::stringstores its size as an integer, and thus does not rely on it.
但是，C++ 类std::string将其大小存储为整数，因此不依赖于它。
回答by Oliver Charlesworth
You're representing strings in two different ways here, which is why the behaviour differs.
您在这里以两种不同的方式表示字符串，这就是行为不同的原因。
The second one is easier to explain; it's a C-style raw char array. In a C-style string, '\0'denotes the null terminator; it's used to mark the end of the string. So any functions that process/display strings will stop as soon as they hit it (which is why your last string is truncated).
第二个更容易解释；它是一个 C 风格的原始字符数组。在 C 风格的字符串中，'\0'表示空终止符；它用于标记字符串的结尾。因此，任何处理/显示字符串的函数都会在遇到它时立即停止（这就是为什么最后一个字符串被截断的原因）。
The first example is creating a fully-formed C++ std::stringobject. These don't assign any special meaning to '\0'(they don't have null terminators).
第一个示例是创建一个完整的 C++std::string对象。它们没有赋予任何特殊含义'\0'（它们没有空终止符）。
回答by Divya Prakash
The \0is treated as NULLCharacter. It is used to mark the end of the string in C.
将\0被视为NULL字符。它用于在 C 中标记字符串的结尾。
In C, string is a pointer pointing to array of characters with \0at the end. So following will be valid representation of strings in C.
在 C 中，字符串是一个指向字符数组的指针，结尾是字符数组\0。因此，以下将是 C 中字符串的有效表示。
The applications of ‘\0' lies in determining the end of string .For eg : finding the length of string.
'\0' 的应用在于确定字符串的结尾。例如：求字符串的长度。
