C语言 将空指针转换为结构体
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Casting a void pointer to a struct
提问by user1852050
I started feeling comfortable with C and then I ran into type casting. If I have the following defined in an *.h file
我开始对 C 感到很舒服，然后我遇到了类型转换。如果我在 *.h 文件中定义了以下内容
struct data {
int value;
char *label;
};
and this in another *.h file
这在另一个 *.h 文件中
# define TYPE void*
How do I cast the void pointer to the struct so that I can use a variable "TYPE val" that's passed into functions? For example, if I want to utilize the value that TYPE val points to, how do I cast it so that I can pass that value to another functions?
如何将 void 指针转换为结构体，以便我可以使用传递给函数的变量“TYPE val”？例如，如果我想利用 TYPE val 指向的值，我如何转换它以便我可以将该值传递给另一个函数？
回答by Alexey Frunze
(struct data*)pointer
will cast a pointer to void to a pointer to struct data.
将指向 void 的指针转换为指向 的指针struct data。
回答by Mahadev
Typecasting void pointer to a struct can be done in following
可以通过以下方式将指向结构的 void 指针类型转换
void *vptr;
typedef struct data
{
/* members */
}tdata;
for this we can typecast to struct lets say u want to send this vptr as structure variable to some function
为此，我们可以将类型转换为 struct 假设您想将此 vptr 作为结构变量发送给某个函数
then
然后
void function (tdata *);
main ()
{
/* here is your function which needs structure pointer
type casting void pointer to struct */
function((tdata *) vptr);
}
Note: we can typecast void pointer to any type, thats the main purpose of void pointers.
注意：我们可以将 void 指针类型转换为任何类型，这就是 void 指针的主要目的。
