西电的VC++课上的几个通用模板,完全是可用的

typedef struct
{
	char btEorW;        // 取值为1,东经; 0,西经;
	char btNorS;        // 取值为1,北纬; 0,南纬;    
	double dLong;       // 经度，取值范围[0.0，180.0)
	double dLat;        // 纬度，取值范围[0.0，90.0]
}ST_GlobePnt;

const char EAST = 1;
const char WEST = 0;
const char NORTH = 1;
const char SOUTH = 0;

const int EXC_OK = 0;        // 0：执行OK，返回值正确；
const int EorW_ERROR = 1;    // 1：东经、西经取值错误；
const int NorS_ERROR = 2;    // 2：南纬、北纬取值错误；
const int LONG_ERROR = 3;    // 3：经度范围越界；
const int LAT_ERROR = 4;     // 4: 纬度范围越界；
const int RADIUS_ERROR = 10;  // 10:半径取值错误(不能小于0)。

const double ACCURACY = 0.00001;    // 精确度 
const double PI = 3.14159265359;
const double radius = 1000.0; // 地球半径

//函数实现
//辅助函数int CheckGPnt(const ST_GlobePnt &a_stPnt)
//功能判断点是否符合要求，实现如下：

int CheckGPnt(const ST_GlobePnt &a_stPnt)
{
    int iRet = EXC_OK; 
    // check if east or west 
    if(a_stPnt.btEorW != EAST && a_stPnt.btEorW != WEST)
    {
        iRet = EorW_ERROR;
        return iRet;
    }
    // check if nort or south
    if(a_stPnt.btNorS != NORTH && a_stPnt.btNorS != SOUTH)
    {
        iRet = EorW_ERROR;
        return iRet;
    }
    // check the range of Long.
    if(a_stPnt.dLong - 180.0 > ACCURACY || a_stPnt.dLong <= - ACCURACY)
    {
        iRet = LONG_ERROR;
        return iRet;        
    }
    // check the range of Lat
    if(a_stPnt.dLat - 90.0 > ACCURACY || a_stPnt.dLat <= -ACCURACY)
    {
        iRet = LAT_ERROR;
        return iRet;
    }    
    return iRet;
}

//接口函数如下：

int CalGlobeDistance(const ST_GlobePnt &a_stPntA,
                    const ST_GlobePnt &a_stPntB,
                    const double &a_dRadius,
                    double &a_dDistance)
{
	int iRet = EXC_OK;    
    a_dDistance = -1.0;

    double dTheta;    // the angle of the two Longs
    double dAlpha;    // the angle of a_stPntA's Lat
    double dBeta;     // the angle of a_stPntB's Lat   
    double dResult;   // the angle of the two lines 
                       //     which one is through the given point and the center
     double dCosResult; // = cos(dResult);

   // Check if the given points is OK --Begin-------    
    iRet = CheckGPnt(a_stPntA);
    if(iRet != EXC_OK)
    {
        return iRet;
    }

    iRet = CheckGPnt(a_stPntB);
    if(iRet != EXC_OK)
    {
        return iRet;
    }

   // Check if the given points is OK --End---------  
   // check the range of Radius
    if(a_dRadius < -ACCURACY)
    {
        iRet = RADIUS_ERROR;
        return iRet;
    }

    dAlpha = a_stPntA.dLat;
    dBeta = a_stPntB.dLat;

    // Calculate the the angle of the two Longs --- Begin --------
    if(a_stPntA.btEorW == a_stPntB.btEorW)
    {
        dTheta = fabs(a_stPntA.dLong - a_stPntB.dLong);    
    }else // !=
    {
        dTheta = a_stPntA.dLong + a_stPntB.dLong;
    }

    if(dTheta - 180.00 > -ACCURACY)
    {
        dTheta = 360.0 - dTheta;
    }
    // Calculate the the angle of the two Longs --- End --------  
	// Change DEGREE to RADIAN     --- Begin ------
    dAlpha = dAlpha / 180.0 * PI;
	dBeta = dBeta / 180.0 * PI;
	dTheta = dTheta / 180.0 * PI;
    // Change DEGREE to RADIAN     --- End ------  
    
	// Calculate the angle of the two lines  --- Begin ---------
    if(a_stPntA.btNorS != a_stPntB.btNorS)
    {
        dCosResult = cos(dAlpha) * cos(dBeta) * cos(dTheta) - sin(dAlpha) * sin(dBeta);
    }else // !=
    {
        dCosResult = cos(dAlpha) * cos(dBeta) * cos(dTheta) + sin(dAlpha) * sin(dBeta);
    }

    dResult = acos(dCosResult);//  dResult ranges [0,Pi],needn't change
    // Calculate the angle of the two lines  --- End ---------
    // Get the distance around the globe

    a_dDistance = a_dRadius * dResult;            
    return iRet;

}