C Typedef and Struct Question

Question

What\'s the difference between these two declarations, and is one preferred over the other?

typedef struct IOPORT {  
    GPIO_TypeDef* port;  
    u16               


        

Answer 1

For the sake of readability it's preferred to express the original example in a form such as:

typedef struct IOPORT_t {  
    GPIO_TypeDef* port;  
    u16           pin;  
} IOPORT; 

....which emphasizes the difference between type and instance.

Furthermore, if you want to add initialisers you can do something like:

typedef struct IOPORT_t {  
    GPIO_TypeDef* port;  
    u16           pin;  
} IOPORT;

struct IOPORT_t IOPORT2 = {
    .port = NULL,
    .pin = 25
  };

or you can lose the typedef to initialise it directly:

struct IOPORT_t {  
    GPIO_TypeDef* port;  
    u16           pin;  
} IOPORT = {
    .port = NULL,
    .pin = 24
  };

struct IOPORT_t IOPORT2 = {
    .port = NULL,
    .pin = 25
  };