什么是创建在C字符串方式之间的区别？ [英] What is the difference between the ways to create a string in C?

问题描述

什么是C语言中这两种形式的字符串变量之间的区别？

What is the difference between these two forms of a string variable in C language?

char *string1;
char string2[];

有没有其他办法做到这一点？

Is there any other way to do it?

非常感谢你。

推荐答案

的char *字符串1 =富;

字符串1是一个指向一个字符串（为参数的缘故，它指向存储在程序的只读数据段的一系列字符）。

string1 is a pointer to a string literal (for the sake of argument, it points to a series of characters stored in a read-only data segment of the program).

字符字符串2 [] =富;

string2为4个字符数组。它被初始化的字节'F'，'O'，'O'，ASCII_NUL。

string2 is an array of 4 characters. It is initialised with the bytes 'f', 'o', 'o', ASCII_NUL.

也许最显著的区别是，如果你做字符串1 [0] ='B'; 你得到了一个未定义的行为，因为你想修改存储重presentation一个字符串。如果你这样做字符串2 [0] ='B'; 则修改您的个人字符串为嘘，这是很好的。

Probably the most significant difference is that if you do string1[0] = 'b'; you get undefined behaviour, because you're trying to modify the stored representation a string literal. If you do string2[0] = 'b'; then you modify your personal string to "boo", which is fine.

在一般情况下，键入的char * 的变量是一个指针为char。它经常被用来指向字符的NULL结尾的序列中的第一个字符，在这种情况下，它指向一个字符串。类型的变量的char [] 是字符数组。如果它有一个NUL终止，那么它实际上是一个字符串。

In general, a variable of type char* is a pointer to a char. It's often used to point to the first char in a NUL-terminated sequence of chars, in which case it points to a string. A variable of type char[] is an array of chars. If it has a NUL terminator, then it actually is a string.

问题是轻微两个事实感到困惑：

The issue is slightly confused by two facts:

1）在C中，每当一个数组变量名中采用一个指针一个上下文中使用，它是指一个指针数组的第一个元素。所以数组和指针经常被认为是可以互换的。

1) In C, whenever an array variable name is used in a context that takes a pointer, it "means" a pointer to the first element of the array. So arrays and pointers are often thought to be interchangeable.

2）在C中，键入的char [] 的函数参数的不的实际上是一个数组。这只是一个指针，完全一样的的char * 。所以，再次，数组和指针经常被认为是可以互换的。

2) In C, a function parameter of type char[] is not in fact an array. It's just a pointer, exactly the same as char*. So, again, arrays and pointers are often thought to be interchangeable.

所以，指针和阵列之间的另一个区别是：

So, another difference between the pointer and the array:

string1 = "bar"; // changes string1 to point to another string literal.

string1 = string2; // changes string1 to point to the first character of string2.

string2 = string1; // doesn't compile - you can't assign to an array,
                   //   only initialize it and then modify element-by-element.

[注：报关字符字符串2 []; 中的问题不是在功能有效C语法，但我已经使用的定义将是有效无论是在一个函数或在文件范围内，任何函数之外。无论哪种方式，他们的行为，因为我已经为初始化和分配说明，但它们有不同的生命周期。]

[Note: the declaration char string2[]; in the question is not valid C syntax in a function, but the definitions I've used would be valid either in a function or at file scope, outside any function. Either way they behave as I've described for initialization and assignment, but they have different lifetimes.]

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