指针静态变量的不便 [英] Inconveniences of pointers to static variables

问题描述

我经常使用便利的函数返回指向静态缓冲区是这样的：

I often use convenience functions that return pointers to static buffers like this:

char* p(int x) {
    static char res[512];

    snprintf(res, sizeof(res)-1, "number is %d", x));

    return res;
}

和使用他们所有的地方作为参数传递给其他功能：

and use them all over the place as arguments to other functions:

...
some_func( somearg, p(6) );
....

不过，这种方便，除了有不是线程安全的一个恼人的缺点（可能还有更多的原因）：

However, this "convenience" has an annoying drawback besides not being thread-safe (and probably many more reasons):

some_func( somearg, p(6), p(7) );

显然以上没有做我想做的，因为最后两个参数将指向相同的内存空间。我希望能够得到上面，而不很多麻烦正常工作。

The above obviously doesn't do what I want since the last two arguments will point to the same memory space. I would like to be able get the above to work properly without to many hassles.

所以我的问题是：

是否有某种神奇的办法，我已经错过了完成我想要的东西没有做繁琐的配置和放大器;释放？

的*更新2010-04-20的 * 的

* UPDATE 2010-04-20 *

无耻插头：看我自己的答案<一个href=\"http://stackoverflow.com/questions/2231317/inconveniences-of-pointers-to-static-variables/2677237#2677237\">here

Shameless plug: look at my own answer here

我想这会工作，但它也接壤矫枉过正。意见？

I guess it will work but it's also bordering to overkill. Opinions?

推荐答案

我发现了一个替代方法。事情是这样的：

I found an alternate method. Something like this:

#define INIT(n) \
 int xi = 0; \
 char *x[n]; \

#define MACRO(s) \
 (++xi, xi %= sizeof(x)/sizeof(*x), x[xi] = alloca(strlen(s)+1), strcpy(x[xi], (s)), x[xi])

这是我可以称之为是这样的：

that I can call like this:

INIT(2);
some_func( somearg, MACRO("testing1"), MACRO("testing2"));

所以缓冲区是在栈上，而无需任何释放。而且它甚至线程安全的。

So the buffers are on the stack without needing any freeing. And it's even thread-safe.

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