#include<math.h>
#include<stdlib.h>
#include<iostream.h>
class Calculator
{
	double a,b;
public:
	Calculator(){a=0;b=0;}; //could be omitted
	void newa()
	{
		double num;
		cout<<"Input the number:";
		cin>>num;
		a=num;
	}
	void newab()
	{
		double num1,num2;
		cout<<"Input the numbers.the first number:";
		cin>>num1;
		cout<<"Input the senond number:";	    
		cin>>num2;
        a=num1;
		b=num2;
	}
	double Geta(){return a;}
	double Getb(){return b;}
	double Add(Calculator &A);
	double Sub(Calculator *A);
	double Mul(Calculator &A);
	double Div(Calculator &A);
	double Sin(Calculator &A);
	double Cos(Calculator &A);
	double Tan(Calculator &A);
	double Exp(Calculator &A);
	double Fabs(Calculator &A);
	double LogE(Calculator &A);
	double Log10(Calculator &A);
	double Pow(double x,double y);
	double Sqrt(double x);
};
double Calculator::Add(Calculator &A)
{
	return A.a+A.b;
}
double Calculator::Sub(Calculator *A)
{
	return A->a-A->b;
}
double Calculator::Mul(Calculator &A)
{
	return A.a*A.b;
}
double Calculator::Div(Calculator &A)
{
	if(A.b==0) 
	{cout<<"Error! The program will be terminated!"<<endl;exit(0);}
	return A.a/A.b;
}
double Calculator::Sin(Calculator &A)
{
	return sin(A.a);
}
double Calculator::Cos(Calculator &A)
{
	return cos(A.a);
}
double Calculator::Tan(Calculator &A)
{
	return tan(A.a);
}
double Calculator::Exp(Calculator &A)
{
	return exp(A.a);
}
double Calculator::Fabs(Calculator &A)
{
	return fabs(A.a);
}
double Calculator::LogE(Calculator &A)
{
	return log(A.a);
}
double Calculator::Log10(Calculator &A)
{
	return log10(A.a);
}
double Calculator::Pow(double x,double y)
{
	return pow(x,y);
}
double Calculator::Sqrt(double x)
{
	if(x<0) 
	{cout<<"Error! The program will be terminated!"<<endl;exit(0);}
	return sqrt(x);
}

void main()
{
	int sel;
	Calculator cal;
	cout<<"Welcome to use the calculator!please select."<<endl;
	cout<<"1:\'+\'    2:\'-\'     3:\'*\'      4:\'/\'     5:\'sin\'   6:\'cos\'  7:\'tan\'"<<endl;
	cout<<"8:\'exp\'  9:\'fabs\'  10:\'logE\'  11:\'log10\' 12:\'pow\'  13:\'sqrt\'"<<endl;
	do
	{
    cout<<"Please select:(0--exit)";
	cin>>sel;
	switch (sel)
	{
	case 0: break;
	case 1: cal.newab();
		    cout<<"The result is:"<<cal.Add(cal)<<endl;
			break;
    case 2: cal.newab();
		    cout<<"The result is:"<<cal.Sub(&cal)<<endl;
			break;
	case 3: cal.newab();
		    cout<<"The result is:"<<cal.Mul(cal)<<endl;
			break;
    case 4: cal.newab();
		    cout<<"The result is:"<<cal.Div(cal)<<endl;
			break;
	case 5: cal.newa();
		    cout<<"The result is:"<<cal.Sin(cal)<<endl;
			break;
    case 6: cal.newa();
		    cout<<"The result is:"<<cal.Cos(cal)<<endl;
			break;
	case 7: cal.newa();
		    cout<<"The result is:"<<cal.Tan(cal)<<endl;
			break;
	case 8: cal.newa();
		    cout<<"The result is:"<<cal.Exp(cal)<<endl;
			break;
	case 9: cal.newa();
		    cout<<"The result is:"<<cal.Fabs(cal)<<endl;
			break;
	case 10: cal.newa();
		    cout<<"The result is:"<<cal.LogE(cal)<<endl;
			break;
	case 11: cal.newa();
		    cout<<"The result is:"<<cal.Log10(cal)<<endl;
			break;
	case 12: cal.newab();
		    cout<<"The result is:"<<cal.Pow(cal.Geta(),cal.Getb())<<endl;
			break;
	case 13: cal.newa();
		    cout<<"The result is:"<<cal.Sqrt(cal.Geta())<<endl;
			break;
	default: cout<<"Your selection is ERROR! Select again!"<<endl;
	}
	}while(sel!=0);
}