C++ “unresolved external symbol” for function outside main

Question

I'm pretty new to C++ and we're working with linked lists and classes. I have my program mostly working but my voidCalc function is giving me the error of:

error LNK2019: 
unresolved external symbol "void __cdecl calcData(class WeatherStats * const,int)"
(?calcData@@YAXQAVWeatherStats@@H@Z) 
referenced in function _main    

I'm only including the main file, if you need the headers for the other two I can add them. Thank you!!

#include "LinkedList.h"
#include "WeatherStats.h"
#include <iostream>
#include <iomanip>
using namespace std;

//Function prototype for highest/lowest
void calcData (WeatherStats stats[], int SIZE);

int main()
{

LinkedList<WeatherStats> weather;
WeatherStats stats;
double rain, snow;
int sun, months;

cout << "Please enter the number of months you would like to report on.\n";
cin >> months;
stats.setMonths(months);

for(int count = 0; count < months; count++)
{
    //Get the information from the user
    stats.setMonths(count+1);
    cout << "Please enter the amount of snow for month " << (count+1) << endl;
    cin >> snow;
    stats.setSnow(snow);
    cout << "Please enter the amount of rain for month " << (count+1) << endl;
    cin >> rain;
    stats.setRain(rain);
    cout << "Please enter the amount of sunny days for month " << (count+1) <<     endl;
    cin >> sun;
    stats.setSun(sun);
    cout << endl;

    //Add the node
    weather.appendNode(stats);
}

weather.displayList();

calcData(&stats, months);

return 0;
}

void calcData (WeatherStats *stats[], int SIZE)
{
int highSun = 0;
int highSunMonth, lowSunMonth, highRainMonth, lowRainMonth, highSnowMonth, lowSnowMonth;
int lowSun = 0;
double lowRain = 0;
double highRain = 0;
double lowSnow = 0;
double highSnow = 0;

for (int count = 1; count <= SIZE; count++)
{
    //Highest Sun and its month
    if(highSun < stats[count]->getSun())
    { highSun = stats[count]->getSun(); 
      highSunMonth = stats[count]->getMonths();
    }

    //Lowest sun and its month
    if (lowSun > stats[count]->getSun())
    { lowSun = stats[count]->getSun();
        lowSunMonth = stats[count]->getMonths();
    }

    //Highest rain and its month
    if(highRain < stats[count]->getRain())
    {
        highRain = stats[count]->getRain();
        highRainMonth = stats[count]->getMonths();
    }

    //Lowest rain and its month
    if (lowRain > stats[count]->getRain())
    {
        lowRain = stats[count]->getRain();
        lowRainMonth = stats[count]->getMonths();
    }

    //Highest snow and its month
    if (highSnow < stats[count]->getSnow())
    {
        highSnow = stats[count]->getSnow();
        highSnowMonth = stats[count]->getMonths();
    }

    //Lowest snow and its month
    if (lowSnow > stats[count]->getSnow())
    {
        lowSnow = stats[count]->getSnow();
        lowSnowMonth = stats[count]->getMonths();
    }

    //Output findings
    cout << "The month with the most sun was Month " << highSunMonth << " with " << highSun << " days.\n";
    cout << "The month with the least sun was Month " << lowSunMonth << " with " << lowSun << " days.\n";
    cout << "The month with the most rain was Month " << highRainMonth << " with " << highRain << " units.\n";
    cout << "The month with the least rain was Month " << lowRainMonth << " with " << lowRain << " units.\n";
    cout << "The month with the most snow was Month " << highSnowMonth << " with " << highSnow << " units.\n";
    cout << "The month with the least snow was Month " << lowSnowMonth << " with " << lowSnow << " units.\n";
}
}

Answer 1

Your function prototype is:

void calcData (WeatherStats stats[], int SIZE);

Your function declaration is:

void calcData (WeatherStats *stats[], int SIZE) { ... }

Those are not the same.

Answer 2

Try declaring the calcData function like this:

void calcData (WeatherStats *stats[], int SIZE);

or this:

extern "C" void calcData (WeatherStats *stats[], int SIZE);

(Please note the extra star added.)

If this doesn't help, make sure to include the library ( .lib or .dll ) defining this function in your linker command line (or in the dependency list in the IDE project settings).

Answer 3

You have a discrepancy with your function prototype and your actual function.

void calcData (WeatherStats stats[], int SIZE);
void calcData (WeatherStats *stats[], int SIZE);

Notice that you have a * in the actual function signature and none in the prototype.