C语言 如何从具有 void 指针的函数中获取字符串

Question

当我尝试从类型为void*的函数中获取字符串时，我只得到第一个字符。

我尝试在不使用的情况下手动复制字符串strcpy()它给了我同样的问题

struct arr {
   int first
   int last.
   void **val; 
};
//I have a function which is called 
void *inspect_arr(const arr *ar, int position)
{
   ....
   return ar->val[offset];
}
//I want to inspect the array so that I can compare the strings
int main()
{
   char *str = calloc(10,sizeof(char));
   char *k = *(char*)inspect_arr(...) //I have a string in the array
  // strcpy(str,k);       Doesn't work
   strcmp(str,k);         Invalid read from valgrind
   //If array has an integer type then I would write my code like this:
   //int a = *(int*)inspect_arr(...) but I can not do the same thing for char
}

运行程序时出现分段错误。

Answer 1

一个问题是第一个* *(char*)inspect_arr(...)。

在那里，您取消引用指针，仅获取第一个字符。相当于((char*)inspect_arr(...))[0].

为了使它更麻烦，然后将此单个字符分配给指针k。这不会k指向字符，而是指向k对应于该字符编码值的任何地址。例如，ASCII 和字符'd'初始化等效于

char *k = 100;