函数指针声明与调用分析

时间： 2021-07-31 作者：daque

hdf5库因变量南针和win32因变量南针示例

hdf5库:

h5_dll herr_t h5aiterate(hid_t loc_id, unsigned *attr_num, h5a_operator_t op,void *op_data)

转到h5a_operator_t设置：

typedef herr_t (*h5a_operator_t)(hid_t location_id/*in*/, const char *attr_name/*in*/, void

*operator_data/*in,out*/);

证明：h5a_operator_t为指向因变量的南针，该南针指向的因变量参数列表与上同；

挪用示例：

//因变量证明

herr_t attr_info(hid_t loc_id, const char *name, void *opdata);

//传播因变量南针给挪用因变量

int idx = h5aiterate(dataset, null, attr_info, null);

win32：

typedef struct tagwndclassexa {

uint cbsize;

/* win 3.x */

uint style;

wndproc lpfnwndproc;

int cbclsextra;

int cbwndextra;

hinstance hinstance;

hicon hicon;

hcursor hcursor;

hbrush hbrbackground;

lpcstr lpszmenuname;

lpcstr lpszclassname;

/* win 4.0 */

hicon hiconsm;

} wndclassexa, *pwndclassexa, near *npwndclassexa, far *lpwndclassexa;

window构造，个中，南针lpfnwndproc指向窗口动静处置因变量，南针东西为指向因变量的南针：

typedef lresult (callback* wndproc)(hwnd, uint, wparam, lparam);

证明：wndproc为指向因变量的南针，不只声领会因变量参数列表，还指定了因变量的挪用办法callback(__stdcall)。

挪用示例：

//因变量证明

lresult callback wndproc (hwnd, uint, wparam, lparam);

//传播因变量南针给构造体分子

wndclassa wndclass ;

wndclass.style = cs_hredraw | cs_vredraw ;

wndclass.lpfnwndproc = wndproc ;

wndclass.cbclsextra = 0 ;

wndclass.cbwndextra = 0 ;

wndclass.hinstance = hinstance ;

wndclass.hicon = loadicon (null, idi_application) ;

wndclass.hcursor = loadcursor (null, idc_arrow) ;

wndclass.hbrbackground = (hbrush) getstockobject (white_brush) ;

wndclass.lpszmenuname = null ;

wndclass.lpszclassname = szappname ;

函数指针声明与调用分析

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