http://www.eyny.com/viewthread.php?tid=5667473

gistfile1.c

// Integrated Development Environment
// Visual C++
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
// 總數量
#define CARSIZE 5
// 一輛車
typedef struct SMyCar
{
	// 車速
	unsigned int m_speed;
	// 超速：1；未超速：0
	unsigned int m_OvrSpd;
}MyCar;
// 很多車
typedef struct SCars
{
	MyCar m_cars[CARSIZE];
	// 總數量
	unsigned int m_Size;
	// 未超速與超速車的數量
	unsigned int m_GdSpd;
	unsigned int m_OvrSpd;
	// 平均時速
	double m_AvgSpd;
	double m_AvgGdSpd;
	double m_AvgOvrSpd;
}Cars;
void InitCars(Cars* cars);
void CopRadar(Cars* cars);
//
int main(int argc, char* argv[])
{
	Cars crs;
	unsigned int i = 0;
	InitCars(&crs);
	for (; i < (crs.m_Size); i ++)
	{
		printf("Input no.%d car\'s speed: ", (i + 1));
		scanf("%u", &(crs.m_cars[i].m_speed));
	}
	CopRadar(&crs);
	for (i = 0; i < (crs.m_Size); i ++)
	{
		printf("No.%d car = %u KmPS ", (i + 1), crs.m_cars[i].m_speed);
		printf("%s\n", ((crs.m_cars[i].m_OvrSpd == 1)?"Speeding":"non-Speeding"));
	}
	printf("2. Speeding cars = %u\n", crs.m_OvrSpd);
	printf("3. Average Speed = %lf\n", crs.m_AvgSpd);
	printf("4. Speeding Average Speed = %lf\n", crs.m_AvgOvrSpd);
	printf("5. non-Speeding Average Speed = %lf\n", crs.m_AvgGdSpd);
	system("PAUSE");
	return (0);
}
void InitCars(Cars* cars)
{
	memset(cars, 0, sizeof(Cars));
	cars->m_Size = CARSIZE;
	//
	// 以下是第二種方法
	//unsigned int i = 0;
	//cars->m_Size = CARSIZE;
	//for (; i < (cars->m_Size); i ++)
	//{
	//	cars->m_cars[i].m_speed = 0;
	//	cars->m_cars[i].m_OvrSpd = 0;
	//}
	//cars->m_GdSpd = 0;
	//cars->m_OvrSpd = 0;
	//cars->m_AvgSpd = 0.0;
	//cars->m_AvgGdSpd = 0.0;
	//cars->m_AvgOvrSpd = 0.0;
}
void CopRadar(Cars* cars)
{
	unsigned int i = 0;
	for (; i < (cars->m_Size); i ++)
	{
		// 未超速
		if ( cars->m_cars[i].m_speed < 110 )
		{
			cars->m_cars[i].m_OvrSpd = 0;
			cars->m_GdSpd ++;
			cars->m_AvgGdSpd += 1.0 * (cars->m_cars[i].m_speed);
		}
		// 超速
		else
		{
			cars->m_cars[i].m_OvrSpd = 1;
			cars->m_OvrSpd ++;
			cars->m_AvgOvrSpd += 1.0 * (cars->m_cars[i].m_speed);
		}
	}
	// 取平均
	cars->m_AvgSpd = cars->m_AvgGdSpd + cars->m_AvgOvrSpd;
	cars->m_AvgSpd /= cars->m_Size;
	cars->m_AvgGdSpd /= cars->m_GdSpd;
	cars->m_AvgOvrSpd /= cars->m_OvrSpd;
}