如何避免免费的（或删除）的长链用C每一个错误检查后？ [英] How to avoid long chain of free's (or deletes) after every error check in C?

问题描述

假如我写我的code非常防守，始终从所有我调用的函数检查返回类型。

Suppose I write my code very defensively and always check the return types from all the functions that I call.

于是我去这样的：

char* function() {
    char* mem = get_memory(100);  // first allocation
    if (!mem) return NULL;

    struct binder* b = get_binder('regular binder');  // second allocation
    if (!b) {
        free(mem);
        return NULL;
    }

    struct file* f = mk_file();  // third allocation
    if (!f) {
        free(mem);
        free_binder(b);
        return NULL;
    }

    // ...
}

注意免费（）的东西如何迅速失控。如果某些功能出现故障，我以前来释放每一个分配。在code很快成为丑陋，我要做的就是复制粘贴一切结束了。我变成了复制/粘贴程序员，更糟的是，如果有人在某处之间增加一个声明，他要修改所有code以下调用免费（）他补充。

Notice how quickly free() things get out of control. If some of the function fails, I have to free every single allocation before. The code quickly becomes ugly and all I do is copy paste everything over. I become a copy/paste programmer, even worse, if someone adds a statement somewhere in between, he has to modify all the code below to call the free() for his addition.

如何有经验的C程序员去了解这个问题呢？我想不出任何东西了。

How do experienced C programmers go about this problem? I can't figure anything out.

谢谢，博大Cydo。

推荐答案

您可以定义一个新的标签的，将释放资源，那么你可以GOTO它时，你的code失败。

You could define a new label that would free the resources and then you could GOTO it whenever your code fails.

char* function()
{
    char* retval = NULL;
    char* mem = get_memory(100);  // first allocation
    if (!mem)
        goto out_error;

    struct binder* b = get_binder('regular binder');  // second allocation
    if (!b)
        goto out_error_mem;

    struct file* f = mk_file();  // third allocation
    if (!f)
        goto out_error_b;

    /* ... Normal code path ... */
    retval = good_value;

  out_error_b:
    free_binder(b);
  out_error_mem:
    free(mem);
  out_error:
    return retval;
}

使用GOTO错误管理已经在这里讨论：
<一href=\"http://stackoverflow.com/questions/788903/valid-use-of-goto-for-error-management-in-c\">http://stackoverflow.com/questions/788903/valid-use-of-goto-for-error-management-in-c

Error management with GOTO was already discussed here: http://stackoverflow.com/questions/788903/valid-use-of-goto-for-error-management-in-c

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