自定义结构体及初始化，以及头文件先声明宏，然后声明结构体
<pre name="code" class="cpp">/********************** macro definition **********************/
#ifndef CVALGO_PI
#define CVALGO_PI 3.141592653589793238462643383
#endif
/********************** structure definition **********************/
/* pixel point information definition */
typedef struct POINT_s {
POINT_s() {
dx = 0.0;
dy = 0.0;
dz = 0.0;
}
double dx; /* Specifies the x-coordinate of point */
double dy; /* Specifies the y-coordinate of point */
double dz; /* Specifies the z-coordinate of point */
}POINT_t;