After reading from a text file, and storing it into a string, I tried to pass this message into another function that will print it out.
This is what it looks like:
http://imgur.com/MCjfRdp
void insert (int id, string message){
    cout << "Inserting " << message << " at" << endl;
}
Somehow the message behind the string overrides the message.
But once I removed the " at" after message, it worked as expected. http://imgur.com/JdHPPmi
 void insert (int id, string message){
    cout << "Inserting " << message << endl;
}
I somehow suspect the problem came from stringstream, but i couldn't find out where.
Here's the code that read from file
    vector <string> line;
fstream infile;
string readLine, tempLine, action, tempLine1;
int level, no;
infile.open(fileName.c_str(),ios::in);
int i = 0;
while (!infile.eof())
{
    getline (infile, readLine);
    line.push_back(readLine);
}
infile.close();
line.pop_back();
for (int i = 0; i < line.size();i++)
{
    stringstream ss (line.at(i));
    getline (ss, action, ' ');
    if (action == "init")
    {
        // some other work here
    }
    else if (action == "insert")
    {
        tempLine = line.at(i);
        ss >> no;
        stringstream iline(tempLine);
        getline (iline, tempLine1, ' ');
        getline (iline, tempLine1, ' ');
        getline (iline, tempLine1, '\n');
        Insert (no, tempLine1);
    }
Since my file has different kinds of actions, here is what test.dat contains:
insert 0 THIS IS A TEST
edit: When i did  file.txt, it came out as something like this.
Inserting THIS IS A TEST
at
Inserting THIS IS TEST NO 2
at