An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant. 这里即是说明:值为0的整型常量表达式,或强制(转换)为 void * 类型的此类表达式,称为 空指针常量 。 如0、0L、3-3、'\0'、017、(void)0等都属于空指针常量。 至于...
49//in the main struct include some sub_strcut 50//we can use first sub_struct pointer to cast(强制转换) the main structure pointer 51// example : sub_strcut pointer = (sub_struct) (the main structure pointer) 52//so we get sub_struct pointer. 53//only by first point 运行结果: *...
The void pointer, also known as the generic pointer, is a special type of pointer that can be pointed at objects of any data type! A void pointer is declared like a normal pointer, using the void keyword as the pointer’s type: #include<stdio.h> #define TRUE 1 #define FALSE 0 int ...
you can pass the int value as void pointer like (void *)&n where n is integer, and in the function accept void pointer as parameter like void foo(void *n);and finally inside the function convert void pointer to int like, int num = *(int *)n;. this way you won't get any warni...
auto c=static_pointer_cast<TYPE>(ptr); 1. 然后取值,输出。 cout<<(*c)->data; 1. 因此,最后的Data可设计为: class Data { public: template<class T> Data(T data){ ptr = std::make_shared<T>(copy(data)); } template<class T> ...
...inti =2; l.elementArray[i] = i;// Intentional usage of pointer as integer// Actual size of pointer does not matter but when i compile i get a bajillion warning: cast to'void *'from smaller integer type'int'[-Wint-to-void-pointer-cast] ...
c语言void*指针是什么 1、void*指针是指针,也指向内存中某个地址的数据,但是内存中的数据类型是不确定的,所以使用时需要转换类型。...2、void的意思是无类型,是无类型指针,可以指向任何类型的数据。因此void指针通常被称为通用指针或泛指针,或万能指针。.../ void *void_pointer_1; void *void_pointer_2; ...
the name of the member within the struct.**/#define container_of(ptr, type, member) ({ \void *__mptr = (void *)(ptr); \BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \!__same_type(*(ptr), void), \"pointer type mismatch in container_of()"); \((ty...
MAX_S宏内(void)(&_x == &_y)语句用于检查参数类型一致性。当参数x和y类型不同时,会产生” comparison of distinct pointer types lacks a cast”的编译警告。 注意,MAX_S和TMAX_S宏虽可避免参数副作用,但会增加内存开销并降低执行效率。若使用者能保证宏参数不存在副作用,则可选用普通定义(即MAX宏)。
libc.myfunc.argtypes = [c_void_p, c_int] #C动态库函数,myfunc(void* str, int len)buf = ctypes.create_string_buffer(256) #字符串缓冲区void_ptr = ctypes.cast(buf,c_void_p)libc.myfunc(void_ptr,256) #在myfunc内填充字符串缓冲区char_ptr = ctypes.cast(void_ptr, POINTER(c_char)) ...