什么是无效铸造吗？ [英] What does void casting do?

问题描述

我读了一些源$ C ​​$ C，这上来;

I was reading some source code, and this came up;

struct Cookie *
Curl_cookie_add(struct SessionHandle *data, /* rest of params were here */)
{
/* unrelated things were here */
#ifdef CURL_DISABLE_VERBOSE_STRINGS
  (void)data;
#endif
/* rest of function goes here */
}

正如你所看到的，无效的指针铸造，甚至没有分配给一个变​​量。我想知道什么是这样做的目的。

As you can see, void casted pointer, isn't even assigned to a variable. I was wondering what is the purpose of this.

推荐答案

本投燮presses，如果不使用数据将出现一个编译器警告。

This cast suppresses a compiler warning that would arise if data is not used.

GCC所产生的这个警告，如果 -Wunused参数标志（由 -Wextra 暗示）已启用。

GCC produces this warning if the -Wunused-parameter flag (implied by -Wextra) is enabled.

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