Method infixToPostfix

Infix_to_Postfix.py:53–86

(self, exp)

    # The main function that converts given infix expression
    # to postfix expression
    def infixToPostfix(self, exp):
        # Iterate over the expression for conversion
        for i in exp:
            # If the character is an operand,
            # add it to output
            if self.isOperand(i):
                self.output.append(i)

            # If the character is an '(', push it to stack
            elif i == "(":
                self.push(i)

            # If the scanned character is an ')', pop and
            # output from the stack until and '(' is found
            elif i == ")":
                while (not self.isEmpty()) and self.peek() != "(":
                    a = self.pop()
                    self.output.append(a)
                if not self.isEmpty() and self.peek() != "(":
                    return -1
                else:
                    self.pop()

                # An operator is encountered
            else:
                while not self.isEmpty() and self.notGreater(i):
                    self.output.append(self.pop())
                self.push(i)

            # pop all the operator from the stack
        while not self.isEmpty():
            self.output.append(self.pop())

        print("".join(self.output))


# Driver program to test above function