#include <iostream.h>
#include <math.h>
#include <string.h>
 
 
 
 
int nVar = 0;
char varName[50];
double varValue[50];
 
double getValue(char ch);
void setValue(char ch, double d);
 
int main()
{
	cout << "This program enables the user to perform Math Functions such as fabs, sqrt, pow, log, log10, sin cos, tan, asin, acos, atan, atan2, sinh, cosh, tanh, ceil, floor, mod. Just input a character(a - z ) followed by an equal sign and the numerical value then press enter. Then in the preceding line input the function you want to use followed by a parenthesis and the alpha character then press enter. To quit, type quit then press enter:\n\n\n";
 
	for(int i = 0; i < 50; i++)
	{
		varName[i] = '(';
	}
 
	char ch;
	char input[6];
	double operand1;
	double operand2;
	double res;
 
	while(1)
	{
		cout << ">>";
 
		cin >> ch;
 
 
		if(ch =='q'|| ch =='Q')
		{
			break;
		}
 
		if(ch =='quit')
		{
			break;
		}
 
 
		input[0] = ch;
 
		operand1 = getValue(ch);
 
		cin >> ch;
		input[1] = ch;
		if(ch == '=')
		{
			cin >> operand1;
 
			setValue(input[0], operand1);
 
			cout << input[0] << "=\n\n\n\t" <<operand1 << "\n";
 
		}
		else
		{
			switch(ch)
			{
			case'+':
 
				cin >> ch;
 
				operand2 = getValue(ch);
 
				res = operand1 + operand2;
 
				cout << "ans=\n\n\n\t" << res << "\n";
				break;
 
			case'-':
 
				cin >> ch;
 
				operand2 = getValue(ch);
 
				res = operand1 - operand2;
 
				cout << "ans=\n\n\n\t" << res << "\n";
				break;
 
			case'*':
 
				cin >> ch;
 
				operand2 = getValue(ch);
 
				res = operand1 * operand2;
 
				cout << "ans=\n\n\n\t" << res << "\n";
				break;
 
			case'/':
 
				cin >> ch;
 
				operand2 = getValue(ch);
 
				res = operand1 / operand2;
 
				cout << "ans=\n\n\n\t" << res << "\n";
				break;
 
			default:
 
 
				cin >> input[2];
				int i = 3;
				while (ch != '(')
				{
					cin >> ch;
					input [i] = ch;
					i++;
				}
 
 
				input[i-1] = '\0';
 
				if(strcmp(input, "sin") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = sin(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "cos") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = cos(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				if(strcmp(input, "tan") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = tan(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				if(strcmp(input, "exp") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = exp(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				if(strcmp(input, "log") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = log(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				if(strcmp(input, "pow") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					cin >> ch;
 
					cin >> ch;
 
					operand2 = getValue(ch);
 
					res = pow(operand1, operand2);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
 
				if(strcmp(input, "asin") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = asin(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "acos") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = acos(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				if(strcmp(input, "atan") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = atan(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "fabs") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = fabs(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "sqrt") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = sqrt(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "ceil") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = ceil(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "sinh") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = sinh(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
				if(strcmp(input, "cosh") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = cosh(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
				if(strcmp(input, "tanh") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = tanh(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "fmod") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = fmod(operand1, operand2);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "floor") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					res = floor(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
 
				}
 
				if(strcmp(input, "log10") == 0)
				{
					cin >> ch;
 
					//cin >> ch;
 
					operand1 = getValue(ch);
 
					res = log10(operand1);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
				if(strcmp(input, "atan2") == 0)
				{
					cin >> ch;
 
					operand1 = getValue(ch);
 
					cin >> ch;
 
					cin >> ch;
 
					res = atan2(operand1, operand2);
 
					cout << "ans=\n\n\n\t" << res << "\n";
 
					cin >> ch;
				}
 
				break;
			}
		}
	}
	return 0;
}
 
 
double getValue(char ch)
{
	for(int i = 0; i < nVar; i++)
	{
		if(ch == varName[i])
		{
			return varValue[i];
		}
	}
	varName[nVar] = ch;
	varValue[nVar] = 0.0;
 
	nVar++;
	return 0.0;
}
 
 
void setValue(char ch, double d)
{
	for(int i = 0; i <nVar; i++)
	{
		if(ch == varName[i])
		{
			varValue[i] = d;
		}
	}
}