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Overloading function needed?

jimmy5023 (159)
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template <class T>
T Geometric(T val1, T val2, T val3)
{
	T v = (1/3);
	T temp;
	temp = (val1 * val2 * val3);
	return (pow(temp,v));
}


pow ambiguous call to overloaded function. Well, in short how to fix it?
GodPyro (151)
Have you overloaded pow() to accept T as a value? As far as I know the default parameters of pow() you can find here:
http://www.cplusplus.com/reference/clibrary/cmath/pow/

To sum it up they are:

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double pow (      double base,      double exponent );
long double pow ( long double base, long double exponent );
float pow (       float base,       float exponent );
double pow (      double base,         int exponent );
long double pow ( long double base,         int exponent );
jimmy5023 (159)
how to overload it? I know how to overload operators like = * / - for vector addition and stuff but i never learn how to overload a function pow. Or do i HAVE to overload it to make this function work? is there any power function that i can use other than pow?
Last edited on
Zap (39)
you could always write your own power function right?

something like:
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mYpow(T num)
{
    return num*num;
}
GodPyro (151)
Just to do what Zap said and to create your own version of the function. e.g.

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pow(T value, int exp)
{

}


it will overload the original as long as the parameters are different.
Last edited on
jimmy5023 (159)
I can't, i still run into the same error. It saids as long as i am using template the error say it might be int, float and stuff. 
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template <class T>
T myPow(T val1,int val2)
{
	return(pow(val1, val2));
}


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template <class T>
T Geometric(T val1, T val2, T val3)
{
	T v = (1/3);
	T temp;
	temp = (val1 * val2 * val3);
	return (myPow(temp, 3));
}

}

GodPyro (151)
You don't understand. You can't throw in pow(T, int) without overloading that function with those parameters. This is what i mean:

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template <class T>
T pow(T val1,int val2)
{
        T result;
	result.value = val1.value * val2;

        return result;
}


Now "val1.value" is something that I made up because I don't have your template definition.
Last edited on
jimmy5023 (159)
What do u mean template definition?

If ur asking for the formula i am going to use is this

(val1 * val2, * val3) ^(1/3) <-- that's what i want to return. the ^ is the power in math not the bitwise operator.
webJose (2948)
Ok, I just have to ask: Given that pow() has 5 overloads shown by the good GodPyro, what in the name of the lord are you passing as type T to your Geometric() function? I mean, it has to be a double, float, int, long double, or maybe long long int (which would be the only one not having an overload).

Also, you have T v = (1/3);. If you know the value of 'v' and you know it is fixed, why declare it of being of the T data type? Why not double v = (1/3);? I am guessing this alone may very well fix your issue.
jimmy5023 (159)
oh, i see. Erm. Alright i will post my complete code and u'll understand. 
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#include <iostream>
#include<cmath>
using namespace std;

template <class T>
T funnyfunc(T val1, T val2, T val3);
template <class T>
T Harmonic(T val1, T val2, T val3);
template <class T>
T Arithmetic(T val1, T val2, T val3);
template <class T>
T Geometric(T val1, T val2, T val3);
void testvalue(int value, short unsigned int code);
void drawmenu(void);
void drawmenu1(void);
template <typename T>
void runprogram();

int main(void)
{

	short unsigned int choice = 0; 
	while(choice!=4)
	{
		cout<<"please select from the following menu ";
		drawmenu();
		cin>>choice;
		try
		{
			testvalue(choice, 3);
			break;
		}

		catch (char* eString)
		{
			cout<< eString <<endl;
			cout<<" please re enter your menu choice ";
		}
	}

	if (choice == 4) 
	{
		cout <<"the program is over";
	}
	else if (choice == 1)
	{
		runprogram<int>();
	}
		
	else if (choice == 2)
	{
		runprogram<float>();
	}
		
	else if (choice == 3)
	{
		runprogram<double>();
	}
	

	




}


template <class T>
T funnyfunc(T val1, T val2, T val3)
{
	return ((val1+val2)*val3);
}

template <class T>
T Harmonic(T val1, T val2, T val3)
{
	return (3/((1/val1)+(1/val2)+(1/val3)));
}

template <class T>
T Arithmetic(T val1, T val2, T val3)
{
	return ((val1 + val2 + val3)/3);
}

template <class T>
T Geometric(T val1, T val2, T val3)
{
	T v = (1/3);
	T temp;
	T n = 3;
	temp = (val1 * val2 * val3);
	return (myPow(temp, (1/n)));
}


void testvalue(int value, short unsigned int code)

{
	switch(code)
	{
	case 1:
		if(value < 0 )
			throw "error - value cannot be negative \n";
			break;
	case 2:
		if(value==0)
			throw "error you can't divided by zero \n";
		break;
	case 3:
		if (value < 1|| value > 4)
			throw "error - invalid menu selection";
		break;
	default:
		cout<<" unhandled exception";
		cout<<"program will stop";
		exit(1);
	}
}

void drawmenu(void)
{
	cout<<endl<<"\t1 - interger"<<endl;
	cout<<"\t2 - float" <<endl;
	cout<<"\t3 - double"<<endl;
	cout<<"\t4 - end this program"<<endl;

}

void drawmenu1(void)
{
	cout<<endl<<"\t1 - Harmonic"<<endl;
	cout<<"\t2 - Arithmetic" <<endl;
	cout<<"\t3 - Geometric"<<endl;
	cout<<"\t4 - end this program"<<endl;

}

template <typename T>
void runprogram()
{
  T a, b, c;
  short unsigned int choice = 0; 

  cout << "please enter first number ";
  cin >> a;
  cout << "please enter second number ";
  cin >> b;
  cout << "please enter third number ";
  cin >> c;

  
  while(choice!=4)
	{
		cout<<"please select what type of means you want ";
		drawmenu1();
		cin>>choice;
		try
		{
			testvalue(choice, 3);
			break;
		}

		catch (char* eString)
		{
			cout<< eString <<endl;
			cout<<" please re enter your menu choice ";
		}
	}

	enum MEAN {HARMONIC = 1, ARITHMETIC,GEOMETRIC};
	MEAN myOps1 = HARMONIC;

		myOps1  = MEAN(choice);
	switch(myOps1)
	{
	case HARMONIC:
		cout<<"the result of Harmonic mean is  " <<Harmonic(a, b, c)<<endl;
		break;
	case ARITHMETIC:
		cout<<"the result of arithmetic mean is " <<Arithmetic(a, b, c)<<endl;
		break;
	case GEOMETRIC:
		cout<<"the result of geometric mean is " <<Geometric(a, b, c)<<endl;
		break;

	default:
		cout<<"thank you for using !"<<endl;
	}

}



So the user got to choose whether it's int/float/double. That's why i would want to make it a template.
THis code ask you "choose int, float, double" then it will ask you "choose harmonic mean, geometric mean, algorithm mean" As i mentioned that's the reason why it's T instead of double/int/float becuase it's what the user choose.
webJose (2948)
Ok, so the problem is with the int datatype because there is no overload that takes int as base. My recommendation: Make a specialization of your function for int. And change the data type of v to double as I suggested earlier.

Oh, and you need to modify the last line: return T(pow(temp, v));
jimmy5023 (159)
How to make a specialize function for int? i call the function in the draw up menu

I mean first thing first i need to correct my currrent function first and right now i still go the same error. 
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template <class T>
T Geometric(T val1, T val2, T val3)
{
	double v = (1/3);
	T temp;
	temp = (val1 * val2 * val3);
	return T(pow(temp, v));
}
webJose (2948)
Ok, that function looks better. To create a specialization, refer to: http://www.cplusplus.com/doc/tutorial/templates/. It shows a specialization of a class, but should be the same for a function (I have never done a specialized function myself).

But let me ask before you proceed: What does the compiler tell you exactly? I would think the compiler is telling you exactly which data type is the problematic one, right?
jimmy5023 (159)
for my previous post the problem is
d:\program files\vs 2010\vc\include\math.h(583): could be 'long double pow(long double,int)'
1> d:\program files\vs 2010\vc\include\math.h(581): or 'long double pow(long double,long double)'
1> d:\program files\vs 2010\vc\include\math.h(535): or 'float pow(float,int)'
1> d:\program files\vs 2010\vc\include\math.h(533): or 'float pow(float,float)'
1> d:\program files\vs 2010\vc\include\math.h(497): or 'double pow(double,int)'
1> d:\program files\vs 2010\vc\include\math.h(122): or 'double pow(double,double)'
1> while trying to match the argument list '(float, double)'
1> d:\spring 2010\cmpsc\cmpsc 122\project7_2\project7_2\project 7_2.cpp(184) : see reference to function template instantiation 'T Geometric<T>(T,T,T)' being compiled
1> with
1> [
1> T=float
1> ]
webJose (2948)
I see, so it is with float, not int. Or maybe it is with int too, but what you show is complaining about float. I see that there is no float pow(float, double), so I guess it is a righteous complaint. Although I cannot help wonder why implicit casting is not taking place.

Anyway, let's get back to making v of type T. This will be good because when T = double, it should have no issues using the overload "double pow(double, double)", and when T = float, it should have no issues using the overload "float pow(float, float)". That leaves us with int. Tehre is nothing even near to "int pow(int, int)". After making variable v of type T, recompile and see the error message. If it throws the error with T = int, then create the template specialization.
jimmy5023 (159)
Here's the error

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template <class T>
T Geometric(T val1, T val2, T val3)
{
	int v = (1/3);
	int temp;
	temp = (val1 * val2 * val3);
	return T(pow(temp, v));
}



1>------ Rebuild All started: Project: project7_2, Configuration: Debug Win32 ------
1> project 7_2.cpp
1>d:\spring 2010\cmpsc\cmpsc 122\project7_2\project7_2\project 7_2.cpp(93): error C2668: 'pow' : ambiguous call to overloaded function
1> d:\program files\vs 2010\vc\include\math.h(583): could be 'long double pow(long double,int)'
1> d:\program files\vs 2010\vc\include\math.h(535): or 'float pow(float,int)'
1> d:\program files\vs 2010\vc\include\math.h(497): or 'double pow(double,int)'
1> while trying to match the argument list '(int, int)'
1> d:\spring 2010\cmpsc\cmpsc 122\project7_2\project7_2\project 7_2.cpp(184) : see reference to function template instantiation 'T Geometric<T>(T,T,T)' being compiled
1> with
1> [
1> T=int
1> ]
1> d:\spring 2010\cmpsc\cmpsc 122\project7_2\project7_2\project 7_2.cpp(47) : see reference to function template instantiation 'void runprogram<int>(void)' being compiled
1>d:\spring 2010\cmpsc\cmpsc 122\project7_2\project7_2\project 7_2.cpp(93): fatal error C1903: unable to recover from previous error(s); stopping compilation
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
webJose (2948)
Jimmy, int v = (1/3); will result in v = 0. Why did you declare it as int? Declare it as T, and then create a specialization for int. Read the link I gave you about templates.
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