初始化一个指针，当字符串字面VS字符数组 [英] String literals vs array of char when initializing a pointer

问题描述

href=\"http://stackoverflow.com/questions/30532077/c-char-array-and-char-pointer\">这个问题。

Inspired by this question.

我们可以用字符串初始化字符指针

We can initialize a char pointer by a string literal:

char *p = "ab";

和它是完全没有问题。
有人可能会认为这等同于以下内容：

And it is perfectly fine. One could think that it is equivalent to the following:

char *p = {'a', 'b', '\0'};

但显然并非如此。而且不仅是因为字符串存储在只读存储器，但现在看来，即使通过字符串文字具有类型字符阵列，并且初始化 {...} 的字符阵列的类型，两个声明的处理方式不同，因为编译器是提出警告：

But apparently it is not the case. And not only because the string literals are stored in a read-only memory, but it appears that even through the string literal has a type of char array, and the initializer {...} has the type of char array, two declarations are handled differently, as the compiler is giving the warning:

警告：在标量初始化多余的元素

warning: excess elements in scalar initializer

在第二种情况下。什么是这种行为的解释？结果

in the second case. What is the explanation of such a behavior?

更新：

此外，在后者的情况下，指针 P 将具有 0x61 的值（第一值数组元素'A'），而不是一个内存位置，这样，编译器，作为警告，以刚刚初始化的第一个元素，并将其分配给 p 。

Moreover, in the latter case the pointer p will have the value of 0x61 (the value of the first array element 'a') instead of a memory location, such that the compiler, as warned, taking just the first element of the initializer and assigning it to p.

推荐答案

我觉得你很困惑，因为的char * p =AB; 和字符p [] =AB; 也有类似的语义，但含义不同。

I think you're confused because char *p = "ab"; and char p[] = "ab"; have similar semantics, but different meanings.

我认为，后一种情况下（字符P [] =AB; ）最好被视为一个的缩写符号的对字符p [] = {'A​​'，'b'，'\\ 0'}; （初始化由初始确定的大小的数组）。其实，在这种情况下，你可以说AB是不是真的作为的字符串的

I believe that the latter case (char p[] = "ab";) is best regarded as a short-hand notation for char p[] = {'a', 'b', '\0'}; (initializes an array with the size determined by the initializer). Actually, in this case, you could say "ab" is not really used as a string literal.

然而，在前一种情况下（的char * p =AB; ）是因为它只是初始化指针不同的 P 指向的只读字符串的AB。

However, the former case (char *p = "ab";) is different in that it simply initializes the pointer p to point to the first element of the read-only string literal "ab".

我希望你能看到其中的差别。而字符P [] =AB; 重新presentable作为初始化，如你所说，的char * p =AB ; 不是，因为指针是，嗯，不是数组，并使用数组初始化初始化它们确实完全不同的东西（也就是给他们的第一个元素的值， 0x61 你的情况）。

I hope you see the difference. While char p[] = "ab"; is representable as an initialization such as you described, char *p = "ab"; is not, as pointers are, well, not arrays, and initializing them with an array initializer does something entirely different (namely give them the value of the first element, 0x61 in your case).

长话短说，只有C编译器替换字符串文字以字符数组初始化它是否适合这样做，也就是说，它被用来初始化字符阵列。

Long story short, C compilers only "replace" a string literal with a char array initializer if it is suitable to do so, i.e. it is being used to initialize a char array.

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