为什么我的程序会崩溃

Question

我猜它与内存分配/删除有关，但我是C ++类的新手。该程序输入一个后缀表达式（来自文件）并生成一系列单操作指令来评估表达式。

#include <iostream>
#include <stack>
#include <fstream>

using namespace std;
class postfixer 
{
public:
    postfixer(string line) 
    {
        char token = 0,
            Rside,
            Lside,
            upper = 'A';
        stack<char>mystack;
        for (int p = 0; p < line.length(); p++) 
        {
            token = line[p];
            if (token >= 'a' && token <= 'z') 
            {
                mystack.push(token);
            }
            else if (token >= '*' && token <= '/') 
            {
                Rside = mystack.top();
                mystack.pop();
                Lside = mystack.top();
                mystack.pop();
                cout << Lside << token << Rside << "=" << upper << endl;
                mystack.push(upper);
                upper++;
            }
        }
        cout << "p = " << mystack.top() << endl;
        cout << "----------------------------" << endl << endl;
    } // constructor definition
};

int main() {
    string line;
    ifstream infile("postfix.txt");//open data file
    if (infile.fail()) 
    { // check to see if the program can connect with the input file
        cout << "can't open the input file";
        //debug: else cout << "input file is open" << endl;
    }
    while (!infile.eof()) 
    {
        getline(infile, line);
        cout << line << endl << endl;
        new postfixer(line);
    }
    return 0;
}

postfix.txt

bced/+*
ab*c+de-/
abdef-/*+
gab/ce*f/-h+*
mc*c*
al*aw*+
lw*