Let's talk about the problem I want to solve. Lets say I have a string dtr which is

dtr = " |post_exp| a   b * c |\post_exp| and |post_exp| (a   b) * c) |\post_exp|."

Now what I am doing is I am pushing data inside first tag (|post_exp| ... |\post_exp|) into the stack variable mudassir. And when I find the second tag I am pushing data inside that tag into another variable mudassir2.

istringstream iss(dtr);
    std::ostringstream oss;
    sstack <string> mudassir;
    sstack <string> mudassir2;
    string subs;
    int count1 = 0;
    string m;
    while (iss >> subs) {
        if (subs == "|post_exp|")
        {
            string ab;
            count1  ;
            if (count1 == 1)
            {
                while (iss >> subs && subs.find("|\\post_exp|") == string::npos)
                {
                    //ab = subs;
                    mudassir.push(subs);


                }
                
        }
            else if (count1 == 2)
            {
                while (iss >> subs && subs.find("|\\post_exp|") == string::npos)
                {
                    //ab = subs;
                    mudassir2.push(subs);


                }
            }

        }
    }
    cout << endl;
    cout << endl;

But the problem is When I pop the data of both stack variables. i.e string m and string u. Output of m=c*b a which is what I want but the output of u=c*b ac)*b) (a which is wrong. It should print c)*b) (a.

while (!mudassir.isempty()) {
        oss << mudassir.gettop();
        mudassir.pop();
    }
    m = oss.str();
    std::cout << m << std::endl;
    string u;
    
        while (!mudassir2.isempty()) {

            oss << mudassir2.gettop();
            mudassir2.pop();
        }
        u = oss.str();
        std::cout << u << std::endl;

CodePudding user response：

You need to make string stream buffer empty.

while (!mudassir.isempty()) {
        oss << mudassir.gettop();
        mudassir.pop();
    }
    m = oss.str();
    oss.str("");
    
    std::cout << m << std::endl;
    string u;
    
        while (!mudassir2.isempty()) {

            oss << mudassir2.gettop();
            mudassir2.pop();
        }
        u = oss.str();
        std::cout << u << std::endl;