[英]How to declare array of structs in C
I am having trouble declaring an array of structs prior to populating them with data. 在用数据填充结构之前,我很难声明一个结构数组。
My struct looks like this: 我的结构看起来像这样:
typedef struct {
uint8_t * p_data; ///< Pointer to the buffer holding the data.
uint8_t length; ///< Number of bytes to transfer.
uint8_t operation; ///< Device address combined with transfer direction.
uint8_t flags; ///< Transfer flags (see @ref NRF_TWI_MNGR_NO_STOP).
} nrf_twi_mngr_transfer_t;
And in my code I am trying to declare the array like this: 在我的代码中,我试图像这样声明数组:
struct nrf_twi_mngr_transfer_t start_read_transfer[10];
However I get a compile error: 但是我得到一个编译错误:
array type has incomplete element type 'struct nrf_twi_mngr_transfer_t'
数组类型的元素类型'struct nrf_twi_mngr_transfer_t'不完整
I have searched around as I thought should be a common thing, but I can't figure out what I am doing wrong. 我进行了搜索,因为我认为这应该很普通,但是我无法弄清楚自己在做什么错。 Maybe because one of the elements is a pointer?
也许因为其中一个元素是指针? But that pointer should be a fixed size right?
但是那个指针应该是固定大小的吧?
Many thanks 非常感谢
It looks like some explanations are in order. 看起来有些解释是适当的。 This code
这段代码
typedef struct {
//...
} nrf_twi_mngr_transfer_t;
Already defines a type which can be used directly. 已经定义了可以直接使用的类型 。 In contrast,
相反,
struct nrf_twi_mngr_transfer_struct {
//...
};
Would define a struct name, and to access it you'd need to indicate that you are referring to a struct. 将定义一个结构名称,要访问它,您需要指出您正在引用一个结构。
As a result, given two definitions above, you should define your arrays differently: 因此,鉴于以上两个定义,您应该以不同的方式定义数组:
nrf_twi_mngr_transfer_t arr[10]; // if using typedef
struct nrf_twi_mngr_transfer_struct arr2[10]; // if using struct with no typedef
And just in case you are wondering, 万一您想知道,
struct {
//...
} nrf_twi_mngr_transfer_obj;
Defines an object of anonymous struct type. 定义一个匿名结构类型的对象。
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