A program thats converts Infix to prefix and then calculates result using prefix equation only in a proper way.

infixtoprefix.cpp

/**************************************************************
    
    Author : Mukul Jain
    Date : 15 Aug 2015
    
    Note : There are lot of cout which I created to
           help me to write this program you can 
           erase them or covert to comment 
           according to convience.
    
*************************************************************/


#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>

using namespace std;


#define max 100

class stack
{
	public :
	
	void push(char x);
	char pop(void);
	bool isEmpty(void);
	bool isFull(void);
	char stackTop(void);
	
	stack();  // Constructor this must be working as createstack
	private :

	int top;
	char a[max];
};

stack :: stack( void )
{
	cout << "Stack has been defined" << endl;
	top = -1;
}

void stack :: push(char x)
{
	if(!this->isFull())
	{	
		cout << "HEY, I just pushed " << x << endl;
		top ++;
		a[top] = x;
	}
	else
	{
		cout << "Sorry Stack is full \n error : Overflow caused" << endl;
	}
}

char stack :: pop (void)
{
	if(this->isEmpty())
	{
		cout << "Sorry the stack is empty" << endl;
		return -1;
	}
	else
	{
		
		char x = a[top];
		top--;
		cout << "I just returned " << x << " through pop" << endl;
		return x;
	}

}

bool stack :: isEmpty (void)
{
	if(top == -1)
	{
		return true;
	}
	else
		return false;

}

bool stack :: isFull(void)
{
	if(top == (max-1))
	{
		return true;
	}
	else
		return false;
}

char stack:: stackTop(void)
{
	if(!this->isEmpty())
	{
		cout << "Topmost value is " << a[top] << endl;
		return a[top];
	}
	else
	{
		cout << "Stack is empty" << endl;
		return -1;
	}	
}


	 
int getweight(char);

int main()
{
	stack stack;
	string S="",T = "";
	int len,i;

	cout << "Target string : " << T << endl;
	cout << "Enter a infix equation : ";

	getline(cin, S);
	
	len = S.size();

	cout << "processing ......." << endl; 

	reverse(S.begin(),
		   S.end());
	 
	cout << "... " << S << " ..."<< endl;

/****************************************************************
					AFTER REVRESING LETS CONVERT 
						INFIX TO POSTFIX
****************************************************************/

	 
	for(i=0; i< len; i++)
	{	

		if(S[i] == ')')
		{
			stack.push(S[i]);
		}

		else if(S[i] == '(')
		{
			
			while( stack.stackTop() != ')')
			{
				
				//cout << "T right now is " << T << endl;
				char t = stack.pop();
				T += t;
			}
			stack.pop();
		}



		else if( (S[i] <= 95 && S[i] >= 63) 
		 || (S[i] <= 122 && S[i] >= 97)	
		 ||	(S[i] <= 57 && S[i] >= 48) )		
		{
			T += S[i];
		}


		else if(S[i] == '$' || '*' || '/' || '+' || '-')
		{
			if(getweight(S[i]) >= getweight(stack.stackTop()))
			{
				stack.push(S[i]);	
			}
			else
			{
				while(stack.stackTop() > S[i])
				{
					T += stack.pop();
				}
				stack.push(S[i]);
			}
		}


	}

	
	bool s = stack.isEmpty();

	cout << "main loop is over" << s << stack.stackTop() << endl;

	while(!stack.isEmpty())
		{
			char t2 = stack.pop();
			T += t2;
		}


	cout << "...... \n ......... \n " << T  << "\n........ \n.........." << endl;

	reverse(T.begin(),
		   T.end());

	cout << "..........\n" << T << endl;


/*****************************************************************
  				NOW COMPUTATION PART
 ****************************************************************/

	len = T.size();
	float temp[2], value=0;
	int j = 0;
	char k;

	for(i=0; i<len; i++)
	{
		if( (T[i] <= 95 && T[i] >= 63) 
		 || (T[i] <= 122 && T[i] >= 97)	
		 ||	(T[i] <= 57 && T[i] >= 48) )		
		{
			cout << "Enter the value of " << T[i] << " : ";
			cin >> temp[j];
			cout << "THe value of j is " << j << " and of temp[j] is " << temp[j] << endl;
			j++;
		}

		else if(T[i] == '$' || '*' || '/' || '+' || '-')
		{
			stack.push(T[i]);
		}

		if(j==2)
		{
			k = stack.pop();

			switch(k)
			{
				case '$':
					value = pow(temp[0],temp[1]);
					break;
				case '*':
					value = temp[0]*temp[1];
					break;
				case '/':
					value = temp[0]/temp[1];
					break;
				case '+':
					value = temp[0]+temp[1];
					break;
				case '-':
					value = temp[0]-temp[1];
					break;
			}

			cout << "value of value is : " << value << endl;

			temp[0] = value;
			j--;
		}	
	}


	return 0;
}

int getweight(char s)
{

	switch(s)
	{
		case '$' : return 3;
		
		case '*' :
		case '/' : return 2;

		case '+' :
		case '-' : return 1;
		
		default : return 0;
	}

}