[英]C cast from specific function pointer to less specific function pointer
Lets say I have the following code in C: 假设我在C中有以下代码:
void general(void (*function)(void *something), void *something);
void funct_type1(struct something1 *something);
void funct_type2(struct something2 *something);
general(funct_type1, something1);
general(funct_type2, something2);
How do I compile this without pointer conversion warnings, and without manually suppressing some errors? 如何在没有指针转换警告的情况下编译它,而无需手动抑制某些错误?
Later edit: I'm trying not to modify funct_type1() and func_type2() definition. 稍后编辑:我正在尝试不修改funct_type1()和func_type2()定义。
The proper fix is to fold the implementation-specific things into the function "behind" the abstract interface, ie: 正确的解决方法是将特定于实现的东西折叠到抽象接口“后面”的函数中,即:
void funct_type1(void *s1)
{
struct something1 *s = s1;
/* ... rest of function ... */
}
Otherwise you're going to have to cast the function pointer in the calls to general()
. 否则,您将不得不在对
general()
的调用中强制转换函数指针。
You can use void *
你可以使用
void *
void general(void (*function)(void *something), void *something);
void funct_type1(void* something);
void funct_type2(void* something);
general(funct_type1, &test1);
general(funct_type2, &test2);
where 哪里
void funct_type1(void* something)
{
struct something1 *castedPointer = something;
//...YOUR STUFF
}
Or you can use an union
to group your structs 或者您可以使用
union
对结构进行分组
#include <stdio.h>
struct something1
{
int a;
};
struct something2
{
int b;
};
union something3
{
struct something1 s1;
struct something2 s2;
};
void general(void (*function)(union something3 *something), union something3* something)
{
if (function != NULL)
function(something);
}
void funct_type1(union something3* something)
{
something->s1.a = 1;
printf("%s - something->s1.a = %d\n", __func__, something->s1.a);
}
void funct_type2(union something3* something)
{
something->s2.b = 3;
printf("%s - something->s2.b = %d\n", __func__, something->s2.b);
}
int main()
{
union something3 test1;
union something3 test2;
test1.s1.a = 0;
test2.s2.b = 0;
general(funct_type1, &test1);
general(funct_type2, &test2);
printf("%s - test1.s1.a = %d\n", __func__, test1.s1.a);
printf("%s - test2.s2.b = %d\n", __func__, test2.s2.b);
}
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