C ++奇怪的问题，未定义的引用 [英] C++ weird problem, Undefined reference

问题描述

获取错误：neljastest.cpp：未定义引用Vector2 :: Vector2（float，float）

neljastest.cpp：

  #include< cstdlib> 
 #include< iostream> 
 #include../include/Vector2.h
 #include../include/neljas.h
 
 using namespace std; 
 
 int main（int argc，char * argv []）{
 Vector2 p1（1.0，2.0）; 
 Vector2 p2（0.0，0.0）; 
 Vector2 p3（5.0，2.0）; 
 return EXIT_SUCCESS; 
} 
  

vector2.h：

  #ifndef VECTOR2_H 
 #define VECTOR2_H 
 
 #include< iostream> 
 using std :: ostream; 
 
 class Vector2 {
 
 public：
 float x; 
 float y; 
 
 Vector2（）; 
 
 Vector2（float nx，float ny）; 
 
 float distanceFrom（Vector2 v）; 
 
 
}; 
 
 
 ostream&运算符<< （ostream& valja，Vector2v）; 
 
 #endif 
  

vector2.cpp：

  #include../include/Vector2.h
 #include< cmath> 
 
 using namespace std; 
 
 Vector2 :: Vector2（）{
 x = 0; 
 y = 0 
} 
 
 Vector2 :: Vector2（float nx，float ny）{
 x = nx; 
 y = ny; 
} 
 
 float Vector2 :: distanceFrom（Vector2 v）{
 return sqrt（（x  -  vx）*（x  -  vx）+（y  -  vy）* -  vy））; 
} 
 
 ostream&运算符<< （ostream& os，Vector2v）{
 return os< （<< v.x<<，<< v.y<<）; 
} 
  

解决方案

C / C ++

似乎在 vector2.cpp 和 neljastest.cpp 您必须更改包含：

  #include../include/Vector2.h
  

To：

  include../include/vector2.h
  

我将所有来源粘贴到同一个文件夹成功编译它们：

  g ++ neljastest.cpp vector2.cpp -o neljastest 
  
 
 
 
 编辑：
 
 
 
您的问题是， neljastest.cpp依赖于src / vector2.cpp，你不是在Makefile上这样做
 
getting error: neljastest.cpp: undefined reference to Vector2::Vector2(float, float)

neljastest.cpp:
    #include <cstdlib>
#include <iostream>
#include "../include/Vector2.h"
#include "../include/neljas.h"

using namespace std;

int main (int argc, char* argv[]) {
     Vector2 p1 (1.0, 2.0);
     Vector2 p2 (0.0, 0.0);
     Vector2 p3 (5.0, 2.0);
    return EXIT_SUCCESS;
}
vector2.h:
#ifndef VECTOR2_H
#define VECTOR2_H

#include <iostream>
using std::ostream;

class Vector2 {

public:
    float x;
    float y;

    Vector2();

    Vector2(float nx, float ny);

    float distanceFrom(Vector2 v);


};


ostream& operator << (ostream& valja, Vector2 v);

#endif
vector2.cpp:
    #include "../include/Vector2.h"
#include <cmath>

using namespace std;

Vector2::Vector2() {
    x = 0;
    y = 0;
}

Vector2::Vector2(float nx, float ny) {
    x = nx;
    y = ny;
}

float Vector2::distanceFrom(Vector2 v) {
    return sqrt( (x - v.x)*(x - v.x) + (y - v.y)*(y - v.y) );
}

ostream& operator << (ostream& os, Vector2 v) {
    return os << "(" << v.x << "," << v.y << ")";
}

解决方案
C/C++ are case sensitive for headers too.

It seems that on vector2.cpp and neljastest.cpp you must change the include from:
#include "../include/Vector2.h"
To:
#include "../include/vector2.h"
I pasted all your sources on the same folder and successfully compiled them with:
g++ neljastest.cpp vector2.cpp -o neljastest
Edit:

Your problem is that the linking process of neljastest.cpp depends on src/vector2.cpp, and you are not doing that on the Makefile

                        
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