Using Pointers in functions - c++

Question

I am trying to use a pointer in my function and then call the function from my main body. When I try to call it I get these 2 errors'; "undefined reference to string output which is caused by the line where I call my stringOutput(); function and the other error is "Id returned 1 exit status." I'm not sure why these errors are occurring.
void stringOutput(int dayNumber, double *ptrTemperatures);
int main()
{
int dayNumber;
double fahrenheit = 0;
double cTemperature = 0;
const double MAXIMUM_TEMPERATURE = 60;// constants for mix/max
const double MINIMUM_TEMPERATURE = -90 ;
const int MAXIMUM_DAYS = 365;
const int MINIMUM_DAYS = 1;
double *ptrTemperatures = NULL;
cout << "How many days would you like to enter? ";
dayNumber = myValidation::GetValidInteger(MINIMUM_DAYS, MAXIMUM_DAYS);
try
{
ptrTemperatures = new double[dayNumber];
}
catch(exception e)
{
cout << "Failed to allocate memory: " << e.what() << endl;
}
cout << "\n\nTEMPERATURE REPORTER\n____________________________\n Please Enter the temperature for each day.";
for(int dayCount = 0; dayCount < dayNumber; dayCount++){
cout << "Celsius Temperature for Day " << (dayCount + 1) << ": ";
ptrTemperatures[dayCount] = myValidation::GetValidDouble(MINIMUM_TEMPERATURE, MAXIMUM_TEMPERATURE);
}
stringOutput();
delete[] ptrTemperatures;
return 0;
}//end main
void stringOutput(int dayNumber, double *ptrTemperatures)
{
cout << "DAILY TEMPERATURE REPORT\n__________________________________-\n\n";
for(int dayCounter = 0; dayCounter < dayNumber; dayCounter++)
{
cout << "Day " << dayCounter << (dayCounter+1) << setw(10) << celsiusToFahrenheit(ptrTemperatures[dayCounter]) << (char(248)) << "F"
<< setw(10) << ptrTemperatures[dayCounter] << (char(248)) << "C" << endl;
}
}

Answer 1

At a guess, your code looks roughly like this:
void stringOutput();
int main()
{
…
stringOutput();
}
void stringOutput(int dayNumber, double *ptrTemperatures)
{
…
}
Your main function uses the stringOutput function you declared above, but that function is never defined anywhere, hence the error.
Below main, you declare and define a separate overload of stringOutput, which has two parameters instead of none.
If you want to use the function you have below main, you need to declare it before main:
void stringOutput(int dayNumber, double *ptrTemperatures);
int main()
…
You also need to give it the arguments it needs, instead of giving it nothing:
int main()
{
…
stringOutput(dayNumber, ptrTemperatures);
}