Question

I have been trying to create a sample application in Visual Studio 2010. I am not getting what is the problem as the code is perfectly compiling, but is giving run-time error. Here is the code:

#include <Map>
#include <string>
#include <sstream>
#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, char* argv[])
{
    map <int, string> *sss = new map<int, string>;
    sss->at(0) = "Jan";
    sss->at(1) = "Feb";
    sss->at(2) = "Mar";
    sss->at(3) = "Apr";
    sss->at(4) = "May";
    sss->at(5) = "Jun";
    string current = NULL;
    ofstream myfile;
    myfile.open("daily_work.txt");
    myfile << "*****   DAILY WORK   *****" << endl;

    for(int i = 0; i < 6; i++)
    {
        string month = sss->at(i);
        for(int j = 1; j < 31; j++)
        {
            stringstream ss;
            ss << j;
            current = ss.str();
            current.append(" ");
            current.append(month);
            current.append(" = ");
            myfile << current << endl;
        }

        current = "";
    }

    printf("Completed!");
    myfile.close();
    sss->clear();
    delete sss;
    sss = NULL;
    return 0;
}

The error is thrown at line no 2 in main.

sss->at(0) = "Jan";

Please find the error here:

Answer 1

Method map.at does access at the element 0. You have just created the map, so you element 0 is empty. Use insert and read this documentation about maps.

c++ reference map

I suggest you also to avoid for 1 ... 6, iterator is the preferred way to cycle a map.
In this way, if you add element to your map, you don’t need to to anything else, the loop will automatically adjust itself.

Use this sample:

typedef std::map<int, string>::iterator it_type;
for(it_type iterator = map.begin(); iterator != map.end(); iterator++) {
    // iterator->first = key
    // iterator->second = value
}