c++ - 多重定义错误——Arduino 库

Question

我正在为 Arduino 构建一个基本的电机库。我正在尝试使用草图 motordrivertest.ino 对其进行测试，但我不断收到整个电机类及其所有方法的多重定义错误。我想知道如何修复这些错误。 (我使用的是 MAC OS X 10.9.3)

这是我的错误。

MotorDriver/motordriver.cpp.o: In function `Motor::getSpeed()':
/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:49: multiple definition of `Motor::getSpeed()'
motordrivertest.cpp.o:/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:49: first defined here
MotorDriver/motordriver.cpp.o: In function `Motor::setSpeed(int)':
/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:33: multiple definition of `Motor::setSpeed(int)'
motordrivertest.cpp.o:/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:33: first defined here
MotorDriver/motordriver.cpp.o: In function `Motor':
/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:15: multiple definition of `Motor::Motor(char)'
motordrivertest.cpp.o:/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:15: first defined here
MotorDriver/motordriver.cpp.o: In function `Motor':
/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:15: multiple definition of `Motor::Motor(char)'
motordrivertest.cpp.o:/Users/pattyborgman/Documents/Arduino/libraries/MotorDriver/motordriver.cpp:15: first defined here

这是我的草图、.h 文件和 .cpp 文件。

motordrivertest.ino

#include "motordriver.h"
#include "motordriver.cpp"

Motor motor('a');

void setup(){}

void loop()
{
 motor.setSpeed(125);
 delay(3000);
 motor.setSpeed(-125);
 delay(3000); 
}

电机驱动.h

#ifndef motordriver_h
#define motordriver_h

#include "Arduino.h"

class Motor
{
public:
    Motor(char letter);
    void setSpeed(int speed);
    int getSpeed();
private:
    int currentSpeed;
    int PWM;
    int BRK;
    int DIR;

};

#endif

电机驱动.cpp

#include "Arduino.h"
#include "motordriver.h"

Motor::Motor(char letter)
{
        if (letter=='a') {
            int PWM = 3;
            int BRK = 9;
            int DIR = 12;
            pinMode(PWM, OUTPUT);
            pinMode(BRK, OUTPUT);
            pinMode(DIR, OUTPUT);
        } else {
            int PWM = 11;
            int BRK = 8;
            int DIR = 13;
            pinMode(PWM, OUTPUT);
            pinMode(BRK, OUTPUT);
            pinMode(DIR, OUTPUT);
        }

}

void Motor::setSpeed(int speed)
{
    currentSpeed=speed;
    if (speed >= 0) {
        analogWrite(PWM, speed);
        digitalWrite(BRK, LOW);
        digitalWrite(DIR, HIGH);
    }else {
        int _speed = -speed;
        analogWrite(PWM, _speed);
        digitalWrite(BRK, LOW);
        digitalWrite(DIR, LOW);
    }

}

int Motor::getSpeed()
{
    return currentSpeed;
}

Answer 1

避免此类错误的简单规则:

• 永远不要#include a .cpp 文件
• 如果你在头文件中实现函数或方法，在它们前面写上inline(模板除外，它们默认是inline)

C(++)-Source-Code 编译成目标文件。对于每个 .cpp 文件，都会生成一个目标文件。这些文件将包含您的函数/方法的机器代码。包含源文件将使您在多个目标文件中具有相同的功能。编译器没问题。编译器运行后，链接器将完成其工作，将所有目标文件和静态库组合成一个可执行文件。现在它找到了几个同名的函数。那它应该怎么办呢？它会通知您它遇到的错误并退出。