c++ - qualified-id 在 '=' token /对象计数器变量之前的声明中

Question

我正在尝试计算有多少个实例或 mole2 类，并将该数字存储在名为 mole_count 的公共(public)静态变量中。

mole2.h

#ifndef mole2_h
#define mole2_h

#include "Arduino.h"
class mole2 {
  public:
    mole2(int input, int output);
    void popUp();
    void popdown();
    boolean moleBrainThinkPopUpNow();
    void setUpTimer(int up_timer);
    boolean didMoleGetHit();
    void setRecoveryTimer(int recovery_timer);
    void decrementRecoveryTimer();
    boolean dosePlayerMistMole();
    void moleReset();

    int input, output;
    static int mole_count;
    static int odds_of_poping;

  private:
    boolean _is_popped = false;

    int _up_timer = 0;
    int _recovery_timer = 0;

};
#endif

mole2.cpp

#include "Arduino.h"
#include "mole2.h"

int mole2::odds_of_poping = 10;

mole2::mole2(int input, int output) {
  input = input;
  output = output;
  int mole2::mole_count = mole2::mole_count + 1;
  pinMode(input, INPUT);
  pinMode(output, OUTPUT);
}

void mole2::popUp() {
  _is_popped = true;
  digitalWrite(input, HIGH);
}

void mole2::popdown() {
  _is_popped = false;
  digitalWrite(input, LOW);
}


boolean mole2::moleBrainThinkPopUpNow() {
  if (_recovery_timer == 0 &&  _is_popped == false && rand() % odds_of_poping == 1) {
  popUp();
    return true;
  }
  else {
    return false;
  }
}

void mole2::setUpTimer(int up_timer) {
  _up_timer = up_timer;
}

boolean mole2::didMoleGetHit() {
  if (_is_popped == true && digitalRead(input) == HIGH) {
    popdown();
    _up_timer = 0;
    return true;
  }
  else {
    return false;
  }
}

void mole2::setRecoveryTimer(int recovery_timer) {
  _recovery_timer = recovery_timer;
}

void mole2::decrementRecoveryTimer() {
  if (_recovery_timer > 0) {
    _recovery_timer--;
  }
}

boolean mole2::dosePlayerMistMole() {
  if (_is_popped == true && _up_timer > 0) {
    _up_timer--;
  }
  if (_is_popped == true && _up_timer == 0) {
    popdown();
    return true;
  }
  else {
    return false;
  }
}

void mole2::moleReset() {
  popdown();
  _up_timer = 0;
  _recovery_timer = 0;
}

完全错误

Arduino: 1.6.12 (Windows 7), Board: "Arduino/Genuino Uno"

C:\Users\Strings\Documents\Arduino\libraries\mole2\mole2.cpp: In constructor 'mole2::mole2(int, int)':

C:\Users\Strings\Documents\Arduino\libraries\mole2\mole2.cpp:9:25: error: qualified-id in declaration before '=' token

   int mole2::mole_count = mole2::mole_count + 1;

                         ^

exit status 1
Error compiling for board Arduino/Genuino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Answer 1

首先是这个:

int mole2::mole_count = mole2::mole_count + 1;

没有任何意义:你在声明一些东西并将它赋值给它的值 + 1

无论如何，您已经在您的类中声明了 mole_count。因为你在构造函数中，所以你已经在 mole2 类中(“qualified-id”位来自这里)，所以你只需要做:

mole_count++;

此外，您必须在 .cpp 类中声明变量的存储并对其进行初始化:

int mole2::mole_count = 0;