谁能给我 _dupenv_s 的示例代码? [英] Can anyone give me example code of _dupenv_s?

问题描述

我正在使用 getenv("TEMP")，但我收到一条警告，告诉我使用 _dupenv_s.

I'm using getenv("TEMP"), but I'm getting a warning telling me to use _dupenv_s.

我在网上找不到 _dupenv_s 的例子.

I can't find an example of _dupenv_s on the net.

文档阅读:

errno_t _dupenv_s(
   char **buffer,
   size_t *numberOfElements,
   const char *varname
);

但是他们指的是什么缓冲区?我只有varname.避免使用缓冲区不是更好吗?

But what buffer are they referring to? I only have varname. Wouldn't it be better to avoid using a buffer?

推荐答案

_dupenv_s 是 Microsoft 的一项功能，设计为一种更安全的 getenv 形式.

_dupenv_s is a Microsoft function, designed as a more secure form of getenv.

_dupenv_s 自己分配缓冲区；您必须向它传递一个指向指针的指针，并将其设置为新分配的缓冲区的地址.

_dupenv_s allocates the buffer itself; you have to pass it a pointer to a pointer and it sets this to the address of the newly allocated buffer.

例如

char* buf = nullptr;
size_t sz = 0;
if (_dupenv_s(&buf, &sz, "EnvVarName") == 0 && buf != nullptr)
{
    printf("EnvVarName = %s\n", buf);
    free(buf);
}

请注意，您负责释放返回的缓冲区.

Note that you're responsible for freeing the returned buffer.

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