Thread: stack usage

I've got this code but I can't for the life of me figure out why I have an unhandled exception:

Code:

#include <iostream>
#include <fstream>
using namespace std;
#include <string>
#include <stack>


class Indent
{
public:
    void processLine(string &str, int lineNum);
    Indent()
    {
        // Handy to push an initial entry on the stack
        // starting at location 0
        m_startingColStack.push(0);
    }
private:
    stack<int> m_startingColStack;
};

void Indent::processLine(string &str, int lineNum)
{
    int len = str.size();
    int startingCol = 0;

    // Find the location of the first non-blank
    // Assuming no TABs, .... TABs would take a little more work here.
    while (str[startingCol] == ' ' && startingCol < len)
        startingCol++;
    
    // Skip completely blank lines
    if (startingCol == len || len == 0)
        return;
    
    // If the new starting line is > top of stack, then push it on stack
    if (startingCol > m_startingColStack.top())
        m_startingColStack.push(startingCol);
    
    // Pop off the stack all of the starting locations > than
    //    the current starting position
    if (m_startingColStack.top() == startingCol && m_startingColStack.size() > 1)
        m_startingColStack.pop();

    // If the top of the remaining stack == the current starting position,
    //    we are in good shape, otherwise we have an error to report
    if (m_startingColStack.top() != startingCol)
        throw "Line is not properly indented!\n";
}

int main()
{
    Indent indent;

	ifstream infile("D://test.txt");
    string str;
    if (!infile)
    {
        cout << "Unable to open input file" << endl;
        cin.get();
        return EXIT_FAILURE;
    }

    try
    {
        string str;
        int lineNum=1;
        while (infile)
        {
            getline(infile, str);
            if (infile)
            {
                indent.processLine(str, lineNum);
            }
            lineNum += 1;
        }
        cout << "Everything is properly indented " << endl;
    }
    catch (string e)
    {
        cout << e << endl;
    }

    cout << "\n\nPress enter to quit...\n\n";
    cin.get();
    return 0;
}

any ideas would be greatly appreciated.

Is it because you're using namespace std before including stack and string?

thanks, that helps a lot! that would have taken a while to find on my own