代码从中缀转换为前缀时遇到问题

Question

我找到了conversion from infix to prefix，我正试图遵循它，但遇到了麻烦。我有大部分内容，但是在比较运营商层次结构方面遇到了麻烦。示例比较\到*。 *获得更高的等级。这是代码。我放 ？？在我遇到麻烦的部分。我使用的语言是c ++。

    string s;
stack<char>operatorStack;
stack<char>operandStack;
char rightOperand;
char leftOperandd;
char operand;
char opera
s = "1 + 2 * ( 1 - 2 - 3 - 4 ) ";


for (int i=0; i<s.length(); i++) {
    if (s[i]!=' ') {
            int arr= s[i];
        cout << arr<<" ";
        if (arr>=48) {
            operandStack.push(s[i]);
        }else {
            if (s[i]=='(' || operatorStack.empty()||??(OperatorHierarchy(token) > OperatorHierarchy(OperatorStack.Top()) )??
                operandStack.push(s[i]);
            else if(s[i]==')'){
                while (operandStack.top()!='(') {
                    opera=operatorStack.top();
                    operatorStack.pop();
                    rightOperand=operandStack.top();
                    operandStack.pop();
                    leftOperandd=operandStack.top();
                    operandStack.pop();
                    operand=opera+rightOperand+leftOperandd;
                    operandStack.push(operand); 
                }
                operatorStack.pop();
            }else if (?? operator hierarchy of token is less than or equal to hierarchy of top of the operator stack  ??) {
                while (!operatorStack.empty() && ??OperatorHierarchy(token) lessThen Or Equal to OperatorHierarchy(OperatorStack.Top()) ) ?? ) {
                    opera=operatorStack.top();
                    operatorStack.pop();
                    rightOperand=operandStack.top();
                    operandStack.pop();
                    leftOperandd=operandStack.top();
                    operandStack.pop();
                    operand=opera+rightOperand+leftOperandd;
                    operandStack.push(operand); 
                }
                operatorStack.push(s[i]);
            }

        }

    }

}
while (!operatorStack.empty()) {
    opera=operatorStack.top();
    operatorStack.pop();
    rightOperand=operandStack.top();
    operandStack.pop();
    leftOperandd=operandStack.top();
    operandStack.pop();
    operand=opera+rightOperand+leftOperandd;
    operandStack.push(operand); 
}
cout << operatorStack.top();
operatorStack.pop();

return 0;
}