常量结构内的函数指针

Question

I'm using a driver written by someone else. To access the driver functions, I have to use a function access struct like the one below: (defined in a header file, say, driver.h )

typedef struct _driver {
  void (*init) (void);           // init is supposed to point to _init
} const driver;                  // problem here with **const**

----------------------------------------------------------------------

void _init (void) {              // defined in another file, say, driver.c
  // init code 
}

How can I make init point to _init ?

The following code works if the driver is not const :

driver dr;
dr.init = &_init;                // modifying directly 
((driver*)(&dr))->init = &_init; // modifying through a pointer

According to the documentation, the driver is supposed to be used as follows:

driver dr;
driver *pdr = &dr;
pdr->init();  

In order for this code to work, dr.init must point _init , but I can't find it anywhere in the code. Any input is greatly appreciated.

Best regards,

Sergey

Answer 1

使用初始化程序 ，例如

driver dr = { _init };

Answer 2

rmartinjak's answer is right, but if you have gcc extensions enabled or using C99 and above, you can use designated initializers . Since your driver struct will probably have more members, this way will probably end up being cleaner looking.

driver dr = {
    .init = _init,
    /* .member = value, */
};