Question

main.cc

#include <iostream>
#include <cstdlib>
#include <string>
#include "gps.h"

using namespace std;

int main(int argc, char  *argv[])
{

  GPScoord  gps1(12.0,13.0);
  GPScoord  gps2(12.0,13.0);

  cout<<gps1.distance_to(gps2)<<endl;

  return 0;
}

gps.h

#ifndef GPS_H
#define GPS_H

class GPScoord {
  public:
  GPScoord(double lat, double longt);

  double lattitude1();
  double longtitude1();
  double rad_lat();
  double rad_long();
  double  distance_to(const GPScoord&  gps );
  private:
  double lattitude;
  double longtitude;
};

#endif

gps.cc

#include <cstdlib>
#include <iostream>
#include <cmath>
#include <math.h>
#include "gps.h"
using namespace  std;

class GPScoord 
{
  private:
  double lattitude;
  double longtitude;
  public:
    GPScoord(double lat,double longt) {

    lattitude=lat;
    longtitude=longt;
  }

  public:
  double lattitude1(){ return lattitude; }
  double longtitude1(){ return longtitude; }
  double rad_lat(){ return lattitude*M_PI/180; }
  double rad_long(){ return longtitude*M_PI/180; }

  double  distance_to(const GPScoord&   gps ){
  double R = 6371e3;
  double radlat = rad_lat();
  double ralong = rad_long();
  double radlat1 = gps.rad_lat();
  double radlong1 = gps.rad_long();
  double radlat2 = radlat-radlat1;
  double radlong2 = ralong-radlong1;
  double          a = pow((sin(radlat2/2)),2)+cos(radlat)*
  cos(radlat1)*pow((sin(radlong2)),2);
  double c=2*atan2(sqrt(a),sqrt(1-a));
  return R*c;
}

};

我收到以下错误：

/tmp/cc13HrVO.o: In function `main':
/home/mustafa/Desktop/main.cc:14: undefined reference to     `GPScoord::GPScoord(double, double)'
/home/mustafa/Desktop/main.cc:15: undefined reference to       `GPScoord::GPScoord(double, double)'
/home/mustafa/Desktop/main.cc:17: undefined reference to   `GPScoord::distance_to(GPScoord const&)'
collect2: error: ld returned 1 exit status

我不明白这个错误，12.0不是双倍还是gps2不是类？我认为这个问题出在gps.h中，但我没有发现这个错误。

Answer 1

首先，您需要编译两个源文件，如下所示：

g ++ -Wall main.cc gps.cc

然后您将看到您收到重新定义类的错误，如解释here所述，可以通过在头文件中定义类然后将类的方法实现到源文件来修复，而无需不得不重新定义课程。

之后你会得到这样的错误：

gps.cc:21:19: error: member function 'rad_lat' not viable: 'this' argument has
      type 'const GPScoord', but function is not marked const
  double radlat = rad_lat();
                  ^~~~~~~

正如编译器所说的那样发生，因为某些函数需要标记为const。将它们放在一起你会得到类似下面的代码：

gps.h：

#ifndef GPS_H
#define GPS_H

class GPScoord {
  public:
  GPScoord(double lat, double longt);

  double lattitude1();
  double longtitude1();
  double rad_lat() const;
  double rad_long() const;
  double  distance_to(const GPScoord&  gps ) const;
  private:
  double lattitude;
  double longtitude;
};

#endif

gps.cc：

#include <cstdlib>
#include <iostream>
#include <cmath>
#include <math.h>
#include "gps.h"
using namespace  std;

GPScoord::GPScoord(double lat,double longt) {

    lattitude=lat;
    longtitude=longt;
}

double GPScoord::lattitude1(){ return lattitude; }
double GPScoord::longtitude1(){ return longtitude; }
double GPScoord::rad_lat() const { return lattitude*M_PI/180; }
double GPScoord::rad_long() const { return longtitude*M_PI/180; }

double  GPScoord::distance_to(const GPScoord&   gps ) const {
  double R = 6371e3;
  double radlat = rad_lat();
  double ralong = rad_long();
  double radlat1 = gps.rad_lat();
  double radlong1 = gps.rad_long();
  double radlat2 = radlat-radlat1;
  double radlong2 = ralong-radlong1;
  double          a = pow((sin(radlat2/2)),2)+cos(radlat)*
  cos(radlat1)*pow((sin(radlong2)),2);
  double c=2*atan2(sqrt(a),sqrt(1-a));
  return R*c;
}

c ++错误“未定义的参考GPScoord：:( double，double）等”

1 个答案: