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More Help With Foiling

ascii (1062)
A few weeks ago I wrote a program to foil two binomials, and its functioning, but I now want to allow the user to enter their own exponents using a caret ^ and then the exponent. It isn't grabbing either of the exponents, however. Please help! Thanks!
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#include<iostream>
#include<cstring>
using std::cout;
using std::cin;
using std::endl;

const int max = 50;

class CFoil		// CFoil class to foil the equation
{
private:
	int coefficient1, coefficient2;		// store the coefficients, exponents, and numbers
	int number1, number2;
	int exponent1, exponent2;
	bool  co1, co2;		// keep track of which number the program needs to get next
	bool num1, num2;
	char* str;

	void calculate();		// calculate and output the answer

public:
	CFoil(char* pstr);		// constructor
	~CFoil();				// deconstructor
	void evaluate();		// evaluate the expression
};

CFoil::~CFoil()
{
	str = NULL;		/* clear the str pointer at the end of each calculation so new data can be entered by the user when
				   the object goes out of scope at the end of each forloop */
}

CFoil::CFoil(char* pstr):
	coefficient1(0), coefficient2(0), number1(0), number2(0), co1(true),
	co2(false), num1(false), num2(false), exponent1(0), exponent2(0)
{
	str = &(*pstr);		// set str to point to the address of the  value pointed to by pstr
}

void CFoil::calculate()
{
	cout << "EXPONENT 1: " << exponent1 
		<< endl << "EXPONENT 2: " << exponent2 
		<< endl;
	cout << coefficient1 * coefficient2 << "x^" << exponent1 + exponent2 << " + "  
		<< (coefficient1 * number2) + (coefficient2 * number1) 
		<< "x + " << number1 * number2 << endl;

	return;
}
void CFoil::evaluate()
{
	for(size_t i = 0; *(str+i) != '\0'; i++)
	{
		while(isdigit(*(str + i)))		// advance past the '*' to the next number
			i++;

		if(num2)	 // grab the second number
		{
			if(*(str+(i)) == '-')	
			{
				while(isdigit(*(str + ++i)))
				{
					number2 *= 10;
					number2 -= *(str+i) - '0';
				}
			}
			else
			{
				while(isdigit(*(str + ++i)))
				{
					number2 *= 10;
					number2 += *(str+i) - '0';
				}
			}
			num2 = false;
			this->calculate();
		}

		if(co2)		// grab the second coefficient
		{	
			if(*(str+i) == '-')
			{
				while(isdigit(*(str + ++i)))
				{
					coefficient2 *= 10;
					coefficient2 -= *(str+i) - '0';
				}
			}
			else
			{
				while(isdigit(*(str + ++i)))
				{
					coefficient2 *= 10;
					coefficient2 += *(str+i) - '0';
				}
			}
			
			if(*(str+i) == '^')
			{
				i++;
				while(isdigit(*(str+i)))
				{
					exponent2 *= 10;
					exponent2 += *(str+i) - '0';
				}
			}
			else
				exponent2 = 1;

			co2 = false;
			num2 = true;
		}
			
		if(num1)	// grab the first number
		{
			if(*(str+i) == '-')
			{
				while(isdigit(*(str + ++i)))
				{
					number1 *= 10;
					number1 -= *(str+i) - '0';
				}
			}
			else
			{
				while(isdigit(*(str + ++i)))
				{
					number1 *= 10;
					number1 += *(str+i) - '0';
				}
			}

			num1 = false;
			co2 = true;
		}
		if(co1)		// grab the first coefficient
		{
			if(*(str+i) == '-')
			{
				while(isdigit(*(str + ++i)))
				{
					coefficient1 *= 10;
					coefficient1 -= *(str+i) - '0';
				}
			}
			else
			{
				while(isdigit(*(str + ++i)))
				{
					coefficient1 *= 10;
					coefficient1 += *(str+i) - '0';
				}
			}
			
			if(*(str+i) == '^')
			{
				i++;
				while(isdigit(*(str+i)))
				{
					exponent1 *= 10;
					exponent1 += *(str+i) - '0';
				}
			}
			else
				exponent1 = 1;
		 
			co1 = false;
			num1 = true;
		}
	}

	return;
}	// end of CFoil

int main(void)
{
	char equation[max];  
	char* pequation = equation;
	cout << "Enter two binomials in parantheses, or an empty line to quit. \nAll variables entered will be converted to \"x\"" << endl;
	for(;;)
	{
		cin.getline(equation, max, '\n');
		CFoil foil(pequation);
		if(!equation[0])
			exit(1);

		for(size_t i = 0; i < strlen(equation); i++)
		{
			if(!isdigit(*(pequation+i)) && *(pequation+i) != '-' && *(pequation+i) != '^')		// turn all non numeric values into *
				*(pequation+i) = '*';
			if(isalpha(*(pequation+i)))
				*(pequation+i) = 'x';	
		}
		foil.evaluate();
	}

	return 0;
}


Last edited on
ascii (1062)
Fixed it, nevermind!
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#include<iostream>
#include<cstring>
using std::cout;
using std::endl;
using std::cin;

const int max = 50;

class CFoil
{
private:
	char* str;
	int index;
	bool num1, co1, ex1;
	int number1, number2, coefficient1, coefficient2, exponent1, exponent2;

	void calculate();
public:
	CFoil(char* str);
	~CFoil();
	void evaluate();
	
};

CFoil::CFoil(char* pstr):
		index(0), co1(true), num1(true), ex1(true), 
		number1(0), number2(0), coefficient1(0),
		coefficient2(0), exponent1(0), exponent2(0)
{
	str = &(*(pstr));
}

void CFoil::evaluate()
{
	while(1)
	{
		switch(*(str+index))
		{
		case '(':		// if there is a opening parantheses get the next number		
			while(isdigit(*(str + ++index)))	
			{
				if(co1)
				{
					coefficient1 *= 10;
					coefficient1 += *(str+index) - '0';		// change from ascii to decimal			
				}
				else
				{
					coefficient2 *= 10;
					coefficient2 += *(str+index) - '0';
				}
			}

			co1 = false;
			break;
		case '+':		// if there is a + sign get the next number
			while(isdigit(*(str + ++index)))
			{
				if(num1)
				{
					number1 *= 10;
					number1 += *(str+index) - '0';
				}
				else
				{
					number2 *= 10;
					number2 += *(str+index) - '0';
				}
			}

			num1 = false;
			break;
		case '-':
			while(isdigit(*(str + ++index)))
			{
				if(num1)
				{
					number1 *= 10;
					number1 -= *(str+index) - '0';
				}
				else
				{
					number2 *= 10;
					number2 -= *(str+index) - '0';
				}
			}
			num1 = false;
			break;
		case '^':			 

			while(isdigit(*(str + ++index)))
			{
				if(ex1)
				{
					exponent1 *= 10;
					exponent1 += *(str+index) - '0';
				}
				else
				{
					exponent2 *= 10;
					exponent2 += *(str+index) - '0';
				}
			}
			ex1 = false;
			break;
		case 'x':
			index++;
			break;
		case ')':		// if there is a ')' or 'x' increment index by 1
			index++;
			break;
		case '\0':		// if at the end of the string
			this->calculate();
			exit(1);
			break;
		default:
			cout << "Syntax error at position: " << index << endl;
			cout << str << endl;
			for(; index > 0; index--)
				cout << " ";
			cout << "^";
			cin.getline(0, 0, '\n');
			exit(1);
		}
	}
}

void CFoil::calculate()
{
	if(exponent1 == 0)
		exponent1 = 1;
	if(exponent2 == 0)
		exponent2 = 1;
	cout << coefficient1 * coefficient2 << "x^" 
		<< exponent1 + exponent2 << " + " 
		<< (coefficient1 * number2) + (coefficient2 * number1)
		<< "x + " << number1 * number2 
		<< endl;

	return;
}

CFoil::~CFoil()
{
	str = NULL;
}

int main(void)
{
	cout << "Enter two binomials in parantheses, or an empty line to quit.  \nUse a caret ^ for exponents." 
		<< endl;
	char str[50] = { 0 };
	char* pstr = str;

	for(;;)
	{
		cin.getline(str, max, '\n');
		
		if(!str[0])
			exit(1);
		for(size_t i = 0; i < strlen(str); i++)
			if(isalpha(*(str+i)))
				*(str+i) = 'x';

		CFoil foil(pstr);
		foil.evaluate();
	}

	return 0;
}
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