*Confused* help please?

[The.Merridian]

I literally just signed up because I'm rather tired of flipping through the stupid text book, so I'm going to admit I'm completely lost :/

I'm using Dev-C++ compiler and it's spitting back the " [Linker error] undefined reference to `getValue(int)' "

I can't figure out why or where my mistake is. It's an assignment for one of my classes. The object of the program is to use user defined functions and have the user input the current year, the current month, their birth year, birth month, and it will tell them how old they are in years and months.

Most of the code was written ahead of time and it's a fill in the blank sort of deal. I'm probably doing it completely wrong.

#include <iostream>
#include <string>
using namespace std;

// user-defined function prototypes
int getValue(int value = 0);
char getLetter(char letter = 'y');
int main()
{
    int thisYear, thisMonth, year, month, ageYear, ageMonth;
    char again = 'y';

   	cout<<"Enter the current year in 4 digit format: ";
   	cin>>thisYear;
        getValue(thisYear);	

	cout<<"Enter the number of the current month: ";
   	cin>>thisMonth;
        getValue(thisMonth);		

	while (again == 'y')
	{
        cout<<"Enter your birth year in 4 digit format: ";
   	cin>>year;
        getValue(year);
    	
	cout<<"Enter the number of your birth month: ";
   	cin>>month;
        getValue(month);

	ageYear = thisYear - year;
	ageMonth = thisMonth - month;

    if (thisMonth < month)
	{
	 	ageYear--;
	 	ageMonth += 12;
	}

	cout<<"\nYou are "<<ageYear<<" years and "<<ageMonth 
        <<"months old.\n";

        cout<<"Would you like to enter another birthday? (y/n)\t";
        cin>>again;
        getLetter(again);

	again = tolower(again);
    }
	
        system("pause");
	return 0;
}

int getValue(string message)
{
       int value;

       cout<<message;
	
	cin>>value;
	
        return value;
}

char getLetter(string message)
{
	char letter;

	cout<<message;
	
	cin>>letter;

	return letter;
}

[redhead]

Look through your code very carefully focusing on your getValue() definition aswell as the function it self, then considder if theres a match between the two ie:
Will this give a hint

int getValue(int value = 0);
...
int getValue(string message)
{...

If not, keep on reading (requires marking the text in order to see)

Since your predefinition of the getValue() function is accepting an int as the argument, it isnt the same as your actual function deifinition which takes a string as the argument, when your main() function is parsed, the parser is knowing the existance of a getValue(int) function, but since theres no actual body of that function, it is never prevailed to teh linker what it actualy does, hence your error.

Since the getValue(int) is known uppon parse time, theres no problem in letting your main() require the

getValue(month);

since its argument is of type int, but once the linking is done it will either result in a segmentation fault, due to the body of the function relying on string type as argument, or a linkage error warning type mismatch.

You either have to redefine your predefinition of the functionint getValue(int); or change the body of the function, aswell as the reference in your main() function ie

thisYear = getValue("Enter the current year in 4 digit format: ")

But since your main() function has the

cout<<"Enter the current year in 4 digit format: ";
cin>>thisYear;

already, you dont need your getValue() function, so you need to decid if you want to change your design according to my suggestion, or get rid of the function itself.

Given that this probably is a lecture in use of calling functions I would suggest you take my advice and change the body of your function to fit your predefinition getValue(string), and change the main() accordingly.

[The.Merridian]

Thank you for your help.

I changed the function body like you suggested and now it's working