C和C之间的字符串字面量的差异++ [英] String Literal Differences Between C and C++
问题描述
据我所知，之前C ++ 11，字符串中几乎完全C和C之间以同样的方式共办理++。
As far as I can tell, before C++11, string literals were handled in almost exactly the same way between C and C++.
现在，我承认，在宽字符串文字的处理C和C ++之间的差异。
Now, I acknowledge that there are differences between C and C++ in the handling of wide string literals.
这是我能找到的唯一区别是在一个阵列由字符串初始化。
The only differences that I have been able to find are in the initialization of an array by string literal.
char str[3] = "abc"; /* OK in C but not in C++ */
char str[4] = "abc"; /* OK in C and in C++. Terminating zero at str[3] */
和技术不同的是只在C ++的问题。在C ++ ABC是为const char [4] ，而在C中，它是的char [ 4] 。不过，C ++有一个特殊的规则，允许转换为为const char * 再到的char * 来留住C兼容性直到C ++ 11时，不再适用的特殊规则。
And a technical difference that only matters in C++. In C++ "abc" is const char [4] while in C it is char [4]. However, C++ has a special rule that allows the conversion to const char * and then to char * to retain C compatibility up until C++11 when that special rule is no longer applied.
和在文字的允许长度的差。然而，作为一个实际问题是任何编译编译C和C ++ code将不执行低级C限制。
And a difference in allowed lengths of literals. However, as a practical matter any compiler that compiles both C and C++ code will not enforce the lower C limit.
我有申请一些相关链接：
I have some interesting links that apply:
- http://david.tribble.com/text/cdiffs.htm
- http://www.coding-guidelines.com/cbook/c90c++.pdf
是否有任何的其他的区别在哪里？
Are there any other differences?
推荐答案
有一个明显的区别是，C ++的字符串是C的人的一个超集。特别是C ++现在支持的原始字符串的（的not用C支持），在技术上§2.14.15定义，一般在HTML和XML用在经常遇到的。
Raw strings
A noticeable difference is that C++'s string literals are a superset of C ones. Specifically C++ now supports raw strings (not supported in C), technically defined at §2.14.15 and generally used in HTML and XML where " is often encountered.
原始字符串允许您指定的形式自己的分隔符（最多16个字符）：
Raw strings allow you to specify your own delimiter (up to 16 characters) in the form:
R"delimiter(char sequence)delimiter"
这是特别有用，通过提供自己的字符串分隔符，以避免不必要的转义字符。下面的两个例子告诉你如何避免逃逸和（分别为：
This is particularly useful to avoid unnecessary escaping characters by providing your own string delimiter. The following two examples show how you can avoid escaping of " and ( respectively:
std::cout << R"(a"b"c")"; // empty delimiter
std::cout << '\n';
std::cout << R"aa(a("b"))aa"; // aa delimiter
// a"b"c"
// a("b")
另一个区别，在评论中指出的那样，是字符串文字具有类型的char [N] 在C，截至§6.4.5/ 6条规定：
Another difference, pointed out in the comments, is that string literals have type char [n] in C, as specified at §6.4.5/6:
有关字符串常量，数组元素具有char类型，并与多字节字符序列的各个字节被初始化。
For character string literals, the array elements have type char, and are initialized with the individual bytes of the multibyte character sequence.
而在C ++他们键入为const char [N] ，如§2.14.5/ 8定义的：
while in C++ they have type const char [n], as defined in §2.14.5/8:
普通字符串文字和UTF-8字符串文字也称为窄字符串。一个箭头
字符串的类型，其中n是定义如下字符串的大小N为const char数组，并有
静态存储持续时间（3.7）。
Ordinary string literals and UTF-8 string literals are also referred to as narrow string literals. A narrow string literal has type "array of n const char", where n is the size of the string as defined below, and has static storage duration (3.7).
这并没有改变，在这两个标准（在§6.4.5/ 7和C和C ++分别2.14.5 / 13）试图在不确定的行为来修改字符串的结果事实。
This doesn't change the fact that in both standard (at §6.4.5/7 and 2.14.5/13 for C and C++ respectively) attempting to modify a string literal results in undefined behavior.
另一个细微的差别是，在C，阉字符串的字符数组不同的是不确定的，因为每§6.4.5/ 7：
Another subtle difference is that in C, wether the character arrays of string literals are different is unspecified, as per §6.4.5/7:
这是不确定的，这些阵列是否提供了不同的元素具有适当的值。
It is unspecified whether these arrays are distinct provided their elements have the appropriate values.
而在C ++中这是实现定义，按照§2.14.5/ 13：
while in C++ this is implementation defined, as per §2.14.5/13:
不管所有的字符串文字是不同的（也就是说，存储在非重叠的对象）是实现定义。
Whether all string literals are distinct (that is, are stored in nonoverlapping objects) is implementation- defined.
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