对C ++中的extern函数的未定义引用

Question

我想问一个有关编译C ++代码时遇到的错误的问题。我在Player.CPP文件中的PSPlayer.CPP和PICost中声明了一个函数“ PSCost”，并在其中调用了此函数。另一个文件。

Commun.cpp

class AlertWakeLock {

    companion object {

        private var wakeLock: PowerManager.WakeLock? = null

        fun acquireWakeLock(context: Context) {
            Log.d(TAG,"Acquiring cpu wake lock")
            if (wakeLock != null) {
                return
            }

            val pm = context.getSystemService(Context.POWER_SERVICE) as PowerManager

            wakeLock = pm.newWakeLock(
                PowerManager.PARTIAL_WAKE_LOCK or
                    PowerManager.ACQUIRE_CAUSES_WAKEUP or
                    PowerManager.ON_AFTER_RELEASE, "ToddlerTimer:WakeLock"
            )
            wakeLock!!.acquire()
        }

        fun releaseWakeLock() {
            Log.d(TAG,"Releasing cpu wake lock")
            if (wakeLock != null) {
                wakeLock!!.release()
                wakeLock = null
            }
        }
    }

}

// ----- commun.cpp -------------

中的函数

#include "Commun.h"
#include <cstdlib>      
#include <algorithm> 
#include "PSPlayer.h"
#include "PIPlayer.h" 

extern float PICost(TRXs trx,int f,Individual * solution,AFP * afpProblem);
extern float PSCost(TRXs trx,int f,Individual * solution,AFP * afpProblem);

，我收到此错误：未定义引用'PSCost（trx，fi，solution，afpProblem）' 拜托，有人可以帮我吗？