// asst5v1.cpp       ALGORITHM DESIGN 306
// arrays of infix strings, postfix strings, operands and operand-values
#include <iostream>
#include <iomanip>             //for setw function to format output
using namespace std;		   //standard namespace
const int LMAX = 50;        //maximum number of infix strings in array
const int NMAX = 30;        //maximum size of each infix string
const int LSIZE = 5;        //actual number of infix strings in the array infix
const int NUMOPNDS = 10;    //number of different operands i.e. A through J
const int MAXSTACK = 100;   //maximum number of items allowed in the stack structures
string InToPost();
void OPNDpush(double);
double OPNDpop();
bool emptystk();
void dumpOPNDstack();
double eValue(char[]);
//array of infix strings
char infix[LMAX][NMAX] = { "A+B-C",
"(A+B)*(C-D)",
"A$B*C-D+E/F/(G+H)",
"((A+B)*C-(D-E))$(F+G)",
"A-B/(C*D$E)" };
//array of postfix strings
char postfix[LMAX][NMAX] = { "AB+C-",
"AB+CD-*",
"AB$C*D-EF/GH+/+",
"AB+C*DE--FG+$",
"ABCDE$*/-" };
//arrays for the operands and their values
char opnd[NUMOPNDS] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J' };
double opndval[NUMOPNDS] = { 3, 1, 2, 5, 2, 4, -1, 3, 7, 187 };
int j;
int IDX;
struct OPERAND_STRAND
{
	int top = -1;
	double item[MAXSTACK];
};
OPERAND_STRAND opndstk;
int main() {

	/*************************************************************************
	PRINT OUT THE OPERANDS AND THEIR VALUES
	**************************************************************************/
	printf("%40s\n\n", "OPERANDS AND THEIR VALUES:");
	for (j = 0; j < NUMOPNDS; j++)
		printf("%5c", opnd[j]);

	printf("\n\n");
	for (j = 0; j < NUMOPNDS; j++)
		printf("%5g", opndval[opnd[j] - 'A']);
	printf("\n\n");
	/*************************************************************************
	PRINT OUT THE INFIX EXPRESSIONS
	**************************************************************************/
	printf("%s\n\n\n","RESULTS");
	printf("%25s%30s%21s\n", "INFIX EXPRESSION", "POSTFIX RESULT", "eVALUE");
	printf("%25s%30s%21s\n", "--------------------", "-------------------", "-----");

	for (j = 0, IDX = j; j < LSIZE; j++, IDX++)  //display name strings & corresponding weights
		printf("%25s%30s%21g\n", infix[j], InToPost().c_str(), eValue(postfix[IDX]));
	system("PAUSE");
	return 0;
}
/****************************************************************************
CONVERSION FUNCTION: INFIX TO POSTFIX NOTATION
****************************************************************************/
string InToPost()
{
	return postfix[IDX];
}

/****************************************************************************
FUNCTION TO DISPLAY INFIX AND POSTFIX EXPRESSIONS
****************************************************************************/
/****************************************************************************
FUNCTION TO EVALUATE THE POSTFIX EXPRESSION
****************************************************************************/
double eValue(char postfix[NMAX])
{
	double evalNum;
	char s;
	double op1;
	double op2;
	double tempVal;
	int k = 0;

	while(postfix[k] != '/0')
	{
		s = postfix[k];

		if (isalpha(s))
			OPNDpush(opndval[s - 'A']);
		else
		{
			op2 = OPNDpop();
			op1 = OPNDpop();
			switch (s)
			{
			case '+': evalNum = op1 + op2;
				break;
			case '-': evalNum = op1 - op2;
				break;
			case '/': evalNum = op1 / op2;
				break;
			case '*': evalNum = op1 * op2;
				break;
			case '$': evalNum = pow(op1, op2);
				break;
			}
			OPNDpush(evalNum);
		}
		k++;
	}
	return evalNum;
}

void OPNDpush(double c)
{
	opndstk.top++;
	opndstk.item[opndstk.top] = c;
}

double OPNDpop()
{
	double c;
	c = opndstk.item[opndstk.top--];
	return c;
}

bool emptystk()
{
	bool r;
	if (opndstk.top == -1)
		r = true;
	else
		r = false;
	return r;
}

void dumpOPNDstack()
{
	if (emptystk())
		printf("| Stack is empty |");
	else
		for (int m = 0; m <= opndstk.top; m++)
		printf("| %g |", opndstk.item[m]);
	printf("\n");
}