C++项目设置，多个定义

我正在进行我的第一个大型C++项目，在正确构建它方面遇到了巨大的问题。

首先，错误：

/tmp/ccn7hjru.o: In function `match(std::basic_istream<char, std::char_traits<char> >&, char const*)':
Geometry.cpp:(.text+0x0): multiple definition of `match(std::basic_istream<char, std::char_traits<char> >&, char const*)'
/tmp/ccfuS3Jb.o:Camera.cpp:(.text+0x0): first defined here
/tmp/ccn7hjru.o: In function `eat(std::basic_istream<char, std::char_traits<char> >&)':
Geometry.cpp:(.text+0xda): multiple definition of `eat(std::basic_istream<char, std::char_traits<char> >&)'
/tmp/ccfuS3Jb.o:Camera.cpp:(.text+0xda): first defined here
/tmp/ccIOhdcQ.o: In function `match(std::basic_istream<char, std::char_traits<char> >&, char const*)':
Light.cpp:(.text+0x0): multiple definition of `match(std::basic_istream<char, std::char_traits<char> >&, char const*)'
/tmp/ccfuS3Jb.o:Camera.cpp:(.text+0x0): first defined here
/tmp/ccIOhdcQ.o: In function `eat(std::basic_istream<char, std::char_traits<char> >&)':
Light.cpp:(.text+0xda): multiple definition of `eat(std::basic_istream<char, std::char_traits<char> >&)'
/tmp/ccfuS3Jb.o:Camera.cpp:(.text+0xda): first defined here
....

这种情况持续了数百行

我所有的c++课程文件都是这样的：

#include "Camera.h"
#include "util.h"
Camera::Camera() {
    // TODO Auto-generated constructor stub
}
Camera::Camera(int x, int y) {
    this->resX = x;
    this->resY = y;
}
Camera::~Camera() {
    // TODO Auto-generated destructor stub
}
...more class methods below...

头文件都是这样的：

#ifndef CAMERA_H_
#define CAMERA_H_
#include "SceneElement.h"
#include "P3D.h"
#include "Ray.h"
#define CAMERA_PRE "{CAM:"
#define CAMERA_POST ":CAM}"
#define TAG_LOCATION "LOC:"
#define TAG_PLANE "PLANE:"
#define TAG_UPPER_RIGHT "UR:"
#define TAG_UPPER_LEFT "UL:"
#define TAG_LOWER_RIGHT "LR:"
#define TAG_LOWER_LEFT "LL:"
#define TAG_RES_X "RESX:"
#define TAG_RES_Y "RESY:"
class Camera: public SceneElement {
public:
    P3D location;
    P3D upperLeft;
    P3D upperRight;
    P3D lowerLeft;
    P3D lowerRight;
    int resX, resY;
    Camera();
    Camera(int, int);
    virtual ~Camera();
    virtual void toStream(std::ostream &);
    virtual void fromStream(std::istream &);
    Ray getRay(int, int);
};
#endif /* CAMERA_H_ */

一个例外是util文件，它看起来像这样：

#include "util.h"
#include <iostream>
#include <stdlib.h>
#include <string.h>

void match(std::istream &str, const char* expected){
    int len = strlen(expected);
    char* fromStream =  (char*)malloc(len+1);
    str.read(fromStream, len);
    fromStream[len] = 0;
    if(strcmp(fromStream, expected)){
        std::cout << "expected " << expected << ", got " << fromStream << "n";
        free(fromStream);
        exit(1);
    }
    free(fromStream);
}

void eat(std::istream &str){
    char c;
    while(c=str.peek(), c == ' ' || c == 'n' || c == 't'){
        str.get();
    }
}

头文件如下：

#ifndef UTILS
#define UTILS
#include <iostream>
void match(std::istream &str, const char* expected);
void eat(std::istream &str);
#endif