如何字符串和字符数组用C的工作？

问题描述

没有指导似乎真的澄清这件事，我已经意识到我真的，真的需要把它直。

我的意思是，你可以为一个char分配内存*变量，或者说的char [25]变量？有什么不同？或者有文字......不能被操纵？......所以如果你要分配一个固定的字符串变量。像如果stringVariable为NULL：stringVariable =thisIsALiteralIsItNotSoWtf，那你怎么处理它

？

有人能以正视听吗？而在最后一种情况下，用文字，你怎么照顾空终止的？这真的只是弄乱我的。

编辑：真正的问题似乎是，我的理解是，你必须为了完成甚至简单的事情忙里忙外，这些不同的结构。例如，只有的char * 可作为一个参数或返回值传递，但只有的char [] 可分配文字和修改。我觉得这是很明显，我们经常/总是需要能够做两件事，那就是我的缺陷是。

解决方案

The lifetime of a malloc-ed string is not limited by the scope of its declaration. In plain language, you can return malloc-ed string from a function; you cannot do the same with char[25] allocated in the automatic storage, because its memory will be reclaimed upon return from the function.

String literals cannot be manipulated in place, because they are allocated in read-only storage. You need to copy them into a modifiable space, such as static, automatic, or dynamic one, in order to manipulate them. This cannot be done:

char *str = "hello";
str[0] = 'H'; // <<== WRONG! This is undefined behavior.

This will work:

char str[] = "hello";
str[0] = 'H'; // <<=== This is OK

This works too:

char *str = malloc(6);
strcpy(str, "hello");
str[0] = 'H'; // <<=== This is OK too

C compiler takes care of null termination for you: all string literals have an extra character at the end, filled with \0.

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