Pyhton 3. Based on the given code of Infix to Postfix conversion, add another fu

Question

Pyhton 3.

Based on the given code of Infix to Postfix conversion, add another function/option for evaluation of the postfix expression. For example, if the user input the infix expression of A + B / C, so the user can evaluate the unknown of A, B and C into any integer or numbers.

class Stack: def init_ _(self) self.items = [] self.length 0 def push (self, val) self.items.append (val) self.length 1 def pop(self) if self.empty): return None self.length1 return self.items .pop) dlef size (self) return self.length def peek(self) if self.empty): return None return self.items [0] def empty(self) return self. length = 0 def tr (self) return str (self.items) precedence precedence [ ' * ' ] = 3 precedence-3 precedenceI'+'-2 precedence--2 precedence''] - 1 def convert (expression) print(__convert (expression.split O)) dlef convert (tokens): postfix -[1 opstack-Stack ) or token in tokens if token.isidentifier: postfix.append (token) opstack.push (token) while True: elif tokenC': elif token'': tempopstack pop) if temp is None or temp' brea elif not temp.isidentifier postfix.append (temp) else: # must be operator if not opstack.empty): temp opstack.peek) while not opstack .empty() and precedence [temp] precedence [token] and token. isidentifier(): >= postfix.append (opstack po) temp opstack.peek (0 opstack-push (token) while not opstack.empty) postfix.append (opstack pop O) return postfix s input ( 'Enter Infix expression : convert (s) ' ) ;

Explanation / Answer

Just Change the Code For the Below Steps :
#Add This Method to your Program.....
# to postfix expression
    def evaluatePostfix(self, exp):
         
        # Iterate over the expression for conversion
        for i in exp:
             
            # If the scanned character is an operand
            # (number here) push it to the stack
            if i.isdigit():
                self.push(i)

            # If the scanned character is an operator,
            # pop two elements from stack and apply it.
            else:
                val1 = self.pop()
                val2 = self.pop()
                self.push(str(eval(val2 + i + val1)))

        return int(self.pop())
          
In convert(expression): method just call the evaluatePostfix method to evaluate the Posfix expression
print(evaluatePostfix(__convert(expression.split()))) juss replace this line in the convert method.
Made this two changes code will work for evaluation also.....

       

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