Need help to get rid of segmentation fault

Hi everyone in the forum. I was just wondering if anyone in this forum could help me get rid of segmentation fault in my programme. The code of the programme is below"

Code:

---

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


//Define a class to represent each Seismic Activity measurement event...


class RedwoodBaySeismicData  {
  string LocationID;          //This is the station that owns this piece of data…
  string Date;                  //The date that the values were collected…
  string Time;                  //The time of day that the values were collected…
  double SeismicSize;        //Magnitude of Earthquake
 


public:
  RedwoodBaySeismicData();
  RedwoodBaySeismicData(string, string, string, double);


  //The first group of member functions are used to change values...
  //Functions are defined in the form of inlines.


  void SetID(string ID)                                        { LocationID = ID; }
  void SetDate(string Day)                        { Date = Day; }
  void SetTime(string Hour)                        { Time = Hour; }
  void SetSeismicSize(double Magnitude)        {SeismicSize = Magnitude; }
 


  //The second group allows controlled access to individual value in the class...


  string GetID()                                { return LocationID; }
  string GetDate()                        {return Date; }
  string GetTime()                        {return Time; }
  double GetSeismicSize()        { return SeismicSize;} 
 


};


//The default constructor sets the private variable members to a harmless value...


RedwoodBaySeismicData::RedwoodBaySeismicData()
{
        LocationID = "";
        Date = "";
        Time = "";
        SeismicSize = 0.0;
       
}


//This initializing  constructor allows you to create a object with value already set...


 RedwoodBaySeismicData::RedwoodBaySeismicData(string ID, string Day, string Hour, double Magnitude)
{
        LocationID = ID;
        Date = Day;
        Time = Hour;
        SeismicSize = Magnitude;
       
}
 
 class RedwoodBayDataList  {
        vector<RedwoodBaySeismicData> RedwoodBayDataSpots;  //Create a collection of location information...
    string FileName ;
public:
        RedwoodBayDataList()  {FileName = "RedwoodBaySeismicEventList.Data";}


   
    void PostSeismicInfo();
    void WeeklyReport();
};








//Allow the user to post the values for each location...


void RedwoodBayDataList::PostSeismicInfo()
{
        int K;
        string Line, ID, Date, Hour;
        double Magnitude;
    fstream InFile("RedwoodBaySeismicEventList.data", ios::in);
        //...then get the values for each location...
        RedwoodBaySeismicData Buffer;




        for(K = 0 ; K < 42 ; K++)  {
         
        getline(InFile, Line);
                ID = Line.substr(0,4);
                Date =  Line.substr(6,7);
                Hour = Line.substr(9,3);
                Magnitude = atof(strtok((char*)Line.c_str(), " ") );
               
               
       
        Buffer.SetID(ID);    //Use these values to load the Buffer record...
                Buffer.SetDate(Date);       
                Buffer.SetTime(Hour);
            Buffer.SetSeismicSize(Magnitude);
        RedwoodBayDataSpots.push_back(Buffer);


                RedwoodBayDataSpots[K].SetID(ID);
                RedwoodBayDataSpots[K].SetDate(Date);
                RedwoodBayDataSpots[K].SetTime(Hour);
                RedwoodBayDataSpots[K].SetSeismicSize(Magnitude);


        cin.ignore(100,'\n');  //This flushes the input buffer of any extra characters.


}


}
//This produces the final product...the report on Seismic Activiies.....


void RedwoodBayDataList::WeeklyReport()
{
        int Count;


    cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
    cout << "\tWeekly Report" << endl;
    cout << "\t===============================================================" << endl;
        cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
    cout << "\t===============================================================" << endl;
        for(Count = 0 ; Count < 42 ; Count++)
                cout << "\t" << RedwoodBayDataSpots[Count].GetID() << "\t" << RedwoodBayDataSpots[Count].GetDate() << "\t" << RedwoodBayDataSpots[Count].GetTime() << "\t"  << RedwoodBayDataSpots[Count].GetSeismicSize();
        cout << "\t===============================================================\n\n" << endl;
}


//Declare the functions...


void RunIT();
void Menu();




int main()
{
        RunIT();
}


//This function implements a simple command processor...


void RunIT()
{
        RedwoodBayDataList RedwoodBayDataSpots;
        string Command = "";


        while(Command != "Quit")  {
                Menu();
                cout << "Command: ";
        getline(cin, Command);


               
            if(Command == "Report")
                        RedwoodBayDataSpots.WeeklyReport();
        }
}


//This function tells the user what he or she can do...


void Menu()
{
        cout << "Choices...................................................." << endl;
        cout << "-----------------------------------------------------------" << endl;
        cout << "\tReport...displays the  report." << endl;
        cout << "\tQuit.....exits the program." << endl;
        cout << "-----------------------------------------------------------" << endl;
}

---

Any help or suggestions will be greatly appreciated.

Have you tried debugging at all? From here it looks like when you run your program and ask for a Report, you attempt to access an index of RedwoodBayDataSpots before ever filling it.

This line is pure evil:

Code:

---

Magnitude = atof(strtok((char*)Line.c_str(), " ") );

---

c_str() return a CONST char*. That means you MUST NOT modify the data that the pointer returned by c_str() points to, and yet that's exactly what you do by casting its constness away and then passing it to strtok(). Don't!

P.S. Worst case scenario: strtok() writes past the memory the string object has allocated for its internal string representation, thereby corrupting its internal state, which (surprise surprise) may lead to all kinds of fun (such as segmentation faults, for instance) later on.


2nd P.S. Okay, I just checked what strtok() actually does, and the scenario I descibed (array bounds violation) is an unlikely consequence, but it's still wrong all the same.

Quote:

---

Originally Posted by System_159

Have you tried debugging at all? From here it looks like when you run your program and ask for a Report, you attempt to access an index of RedwoodBayDataSpots before ever filling it.

---

To add to System_159's post, since you're already using vectors and string objects, consider using their at()-methods instead of [] to access individual elements by index. at() will raise an exception if it detects an out-of-bounds access whereas operator [] will just silently ignore the problem.

Quote:

---

Originally Posted by antred

This line is pure evil:

Code:

---

Magnitude = atof(strtok((char*)Line.c_str(), " ") );

---

c_str() return a CONST char*. That means you MUST NOT modify the data that the pointer returned by c_str() points to, and yet that's exactly what you do by casting its constness away and then passing it to strtok(). Don't!

P.S. Worst case scenario: strtok() writes past the memory the string object has allocated for its internal string representation, thereby corrupting its internal state, which (surprise surprise) may lead to all kinds of fun (such as segmentation faults, for instance) later on.


2nd P.S. Okay, I just checked what strtok() actually does, and the scenario I descibed (array bounds violation) is an unlikely consequence, but it's still wrong all the same.

---

Hi Antred. Thanks for your response. The thing is that since "Magnitude" is a double variable, I can not read it from the file by using "substr" like I did for other variables. Do you happen to know any other way (without using "strtok") to read the "Magnitude" from the file in this case?

You could hack up a little utility function:

Code:

---

#include <sstream>

template < typename TargetType >
TargetType fromString( const std::string& theString )
{
    std::istringstream myStream( theString );
    TargetType t = TargetType();
    myStream >> t;
    return t;
}

---

And then use it to extract your double:

Code:

---

Magnitude = fromString< double >( Line );

---

Quote:

---

Originally Posted by antred

You could hack up a little utility function

---

Or if Boost is available, you could use boost::lexical_cast, which is more comprehensive and does additional error checking.

By the way, I don't see the point of writing:

Code:

---

TargetType t = TargetType();

---

since it would be simpler to write:

Code:

---

TargetType t;

---

Quote:

---

Originally Posted by laserlight

By the way, I don't see the point of writing:

Code:

---

TargetType t = TargetType();

---

since it would be simpler to write:

Code:

---

TargetType t;

---

---

Did that just to enforce default initialization for built-in types.

Then you're relying on the myStream >> t; line to not modify t if the data in the string cant be converted to that type right?

It might be a bug but when I tried to do that with an unsigned int in gcc it changed the value of the variable even when the string clearly was not convertible to unsigned int. The assumption seemed to hold for other types though.

Quote:

---

Originally Posted by antred

Did that just to enforce default initialization for built-in types.

---

I believe that is technically value initialisation, but anyway boost::lexical_cast just throws an exception. In my opinion, this is better than following atoi's approach since you cannot differentiate between say, 0 being a valid result of a conversion to int and 0 being the result of a failed conversion.

First, thanks everyone for their sound and erudite advices. But, I would just like to point out that I am not in anyway advanced programmer. As a matter of fact I just started learning C++ about two months ago. So, some of the advices that I got from people here were beyond my ability to understand. Anyway, I did a research for a day about all those topics and options you guys brought here in this thread. However, it seems like it is going take more than a day for sure to be familiar with all those advanced materials. Anyway, in the meantime I came up with a simple solution for my problem. As many of you point it out that the use of c_str() might be contributing for the rise of segmentation fault, i decided not to use it anymore. So, now I am reading the double variable "Magnitude" with the help of stringstream. However, contrary to what I expected, the programme is still suffering from segmentation fault.
Here is the modified code for the programme:

Code:

---


#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
using namespace std;

//Define a class to represent each Seismic Activity measurement event...

class RedwoodBaySeismicData  {
  string LocationID;  //This is the station that owns this piece of data…
  string Date;    //The date that the values were collected…
  string Time;    //The time of day that the values were collected…
  double SeismicSize;  //Magnitude of Earthquake
 

public:
  RedwoodBaySeismicData();
  RedwoodBaySeismicData(string, string, string, double);

  //The first group of member functions are used to change values...
  //Functions are defined in the form of inlines.

  void SetID(string ID)    { LocationID = ID; }
  void SetDate(string Day)  { Date = Day; }
  void SetTime(string Hour)  { Time = Hour; }
  void SetSeismicSize(double Magnitude) {SeismicSize = Magnitude; }
 

  //The second group allows controlled access to individual value in the class...

  string GetID()    { return LocationID; }
  string GetDate()  {return Date; }
  string GetTime()  {return Time; }
  double GetSeismicSize() { return SeismicSize;} 
 

};

//The default constructor sets the private variable members to a harmless value...

RedwoodBaySeismicData::RedwoodBaySeismicData()
{
 LocationID = "";
 Date = "";
 Time = "";
 SeismicSize = 0.0;
 
}

//This initializing  constructor allows you to create a object with value already set...

 RedwoodBaySeismicData::RedwoodBaySeismicData(string ID, string Day, string Hour, double Magnitude)
{
 LocationID = ID;
 Date = Day;
 Time = Hour;
 SeismicSize = Magnitude;
 
}
 
 class RedwoodBayDataList  {
 vector<RedwoodBaySeismicData> RedwoodBayDataSpots;  //Create a collection of location information...
    string FileName ;
public:
 RedwoodBayDataList()  {FileName = "RedwoodBaySeismicEventList.Data";}

   
    void PostSeismicInfo();
    void WeeklyReport();
};
 
 
 

//Allow the user to post the values for each location...

void RedwoodBayDataList::PostSeismicInfo()
{
 int K;
 string Line, ID, Date, Hour;
 double Magnitude;
    fstream InFile("RedwoodBaySeismicEventList.data", ios::in);
 //...then get the values for each location...
 RedwoodBaySeismicData Buffer;
 

 for(K = 0 ; K < 42 ; K++)  {
         
        getline(InFile, Line);
  ID = Line.substr(0,4);
  Date =  Line.substr(6,7);
  Hour = Line.substr(9,3);
  istringstream buf(Line.substr(5,2));
        buf>> Magnitude;
 
 
       
        Buffer.SetID(ID);    //Use these values to load the Buffer record...
  Buffer.SetDate(Date);
  Buffer.SetTime(Hour);
      Buffer.SetSeismicSize(Magnitude);
        RedwoodBayDataSpots.push_back(Buffer);

  RedwoodBayDataSpots[K].SetID(ID);
  RedwoodBayDataSpots[K].SetDate(Date);
  RedwoodBayDataSpots[K].SetTime(Hour);
  RedwoodBayDataSpots[K].SetSeismicSize(Magnitude);

 cin.ignore(100,'\n');  //This flushes the input buffer of any extra characters.

}

}
//This produces the final product...the report on Seismic Activiies.....

void RedwoodBayDataList::WeeklyReport()
{
 int Count;

    cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
    cout << "\tWeekly Report" << endl;
    cout << "\t===============================================================" << endl;
 cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
    cout << "\t===============================================================" << endl;
 for(Count = 0 ; Count < 42 ; Count++)
  cout << "\t" << RedwoodBayDataSpots[Count].GetID() << "\t" << RedwoodBayDataSpots[Count].GetDate() << "\t" << RedwoodBayDataSpots[Count].GetTime() << "\t"  << RedwoodBayDataSpots[Count].GetSeismicSize();
        cout << "\t===============================================================\n\n" << endl;
}

//Declare the functions...

void RunIT();
void Menu();
 

int main()
{
 RunIT();
}

//This function implements a simple command processor...

void RunIT()
{
 RedwoodBayDataList RedwoodBayDataSpots;
 string Command = "";

 while(Command != "Quit")  {
  Menu();
  cout << "Command: ";
        getline(cin, Command);

 
    if(Command == "Report")
  RedwoodBayDataSpots.WeeklyReport();
 }
}

//This function tells the user what he or she can do...

void Menu()
{
 cout << "Choices...................................................." << endl;
 cout << "-----------------------------------------------------------" << endl;
 cout << "\tReport...displays the  report." << endl;
 cout << "\tQuit.....exits the program." << endl;
 cout << "-----------------------------------------------------------" << endl;
}

---

In your void RedwoodBayDataList::WeeklyReport() function you are trying to access elements of your vector before you add any elements to this vector. In the following snippet:

Code:

---

void RedwoodBayDataList::WeeklyReport()
{
 int Count;
....
 for(Count = 0 ; Count < 42 ; Count++)
  cout << "\t" << RedwoodBayDataSpots[Count].GetID() << "\t" << RedwoodBayDataSpots[Count].GetDate() << "\t" << RedwoodBayDataSpots[Count].GetTime() << "\t"  << RedwoodBayDataSpots[Count].GetSeismicSize();

---

There are no elements in your RedwoodBayDataSpots vector, it looks like you need to read your file and add items to the vector so you can print your report.

Jim

Your indentation is also all over the place. You should be consistent in indenting your code.

What you should be doing in WeeklyReport is using the size of the vector as your bounds for iterating over it (or using an iterator). Here's an example of the first:

Code:

---

void RedwoodBayDataList::WeeklyReport()
{
    cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
    cout << "\tWeekly Report" << endl;
    cout << "\t===============================================================" << endl;
    cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
    cout << "\t===============================================================" << endl;
    for(size_t Count = 0; Count < RedwoodBayDataSpots.size() ; ++Count)
      cout << "\t" << RedwoodBayDataSpots[Count].GetID() << "\t" << RedwoodBayDataSpots[Count].GetDate() << "\t" << RedwoodBayDataSpots[Count].GetTime() << "\t"  << RedwoodBayDataSpots[Count].GetSeismicSize();
    cout << "\t===============================================================\n\n" << endl;
}

---

Even better would be to overload the stream insertion operator ( << ) for the RedwoodBaySeismicData class, so that becomes as simple as:

Code:

---

void RedwoodBayDataList::WeeklyReport()
{
    cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
    cout << "\tWeekly Report" << endl;
    cout << "\t===============================================================" << endl;
    cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
    cout << "\t===============================================================" << endl;
    for(size_t Count = 0; Count < RedwoodBayDataSpots.size() ; ++Count)
      cout <<RedwoodBayDataSpots[Count];
    cout << "\t===============================================================\n\n" << endl;
}

---

Hi forum. I was busy doing other stuff, so I could not take part in the discussion yesterday. But, anyway, as per the advice of rags_to_riches and jimblumberg, I have made some modifications on my code. And, thanks to both as my programme does not suffer from segmentation fault anymore. However, the programme is still not being able to read the data from the file. Here is the modified code for the programme:

Code:

---


#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
using namespace std;
//Define a class to represent each Seismic Activity measurement event...
class RedwoodBaySeismicData {
string LocationID; //This is the station that owns this piece of data…
string Date; //The date that the values were collected…
string Time; //The time of day that the values were collected…
double SeismicSize; //Magnitude of Earthquake

public:
RedwoodBaySeismicData();
RedwoodBaySeismicData(string, string, string, double);
//The first group of member functions are used to change values...
//Functions are defined in the form of inlines.
void SetID(string ID) { LocationID = ID; }
void SetDate(string Day) { Date = Day; }
void SetTime(string Hour) { Time = Hour; }
void SetSeismicSize(double Magnitude) {SeismicSize = Magnitude; }

//The second group allows controlled access to individual value in the class...
string GetID() { return LocationID; }
string GetDate() {return Date; }
string GetTime() {return Time; }
double GetSeismicSize() { return SeismicSize;}


};
//The default constructor sets the private variable members to a harmless value...
RedwoodBaySeismicData::RedwoodBaySeismicData()
{
LocationID = "";
Date = "";
Time = "";
SeismicSize = 0.0;

}
//This initializing constructor allows you to create a object with value already set...
RedwoodBaySeismicData::RedwoodBaySeismicData(string ID, string Day, string Hour, double Magnitude)
{
LocationID = ID;
Date = Day;
Time = Hour;
SeismicSize = Magnitude;

}

class RedwoodBayDataList {
vector<RedwoodBaySeismicData> RedwoodBayDataSpots; //Create a collection of location information...
string FileName ;
public:
RedwoodBayDataList() {FileName = "RedwoodBaySeismicEventList.data";}

void PostSeismicInfo();
void WeeklyReport();
};



//Allow the user to post the values for each location...
void RedwoodBayDataList::PostSeismicInfo()
{
int K;
string Line, ID, Date, Hour;
double Magnitude;
fstream InFile("RedwoodBaySeismicEventList.data", ios::in);
//...then get the values for each location...
RedwoodBaySeismicData Buffer;

cout << "\n\t=============================================================" << endl; //This section is the report...it's really all about the formatting...
cout << "\tWeekly Report" << endl;
cout << "\t===============================================================" << endl;
cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
cout << "\t===============================================================" << endl;

for(size_t K = 0; K < RedwoodBayDataSpots.size(); ++K) {

getline(InFile, Line);
ID = Line.substr(0,4);
Date = Line.substr(6,7);
Hour = Line.substr(9,3);
istringstream buf(Line.substr(5,2));
buf>> Magnitude;

RedwoodBayDataSpots[K].SetID(ID);
RedwoodBayDataSpots[K].SetDate(Date);
RedwoodBayDataSpots[K].SetTime(Hour);
RedwoodBayDataSpots[K].SetSeismicSize(Magnitude);
cout << "\t" << RedwoodBayDataSpots[K].GetID() << "\t" << RedwoodBayDataSpots[K].GetDate() << "\t" << RedwoodBayDataSpots[K].GetTime() << "\t" << RedwoodBayDataSpots[K].GetSeismicSize();
}
cout << "\t===============================================================\n\n" << endl;

}



//Declare the functions...
void RunIT();
void Menu();

int main()
{
RunIT();
}
//This function implements a simple command processor...
void RunIT()
{
RedwoodBayDataList RedwoodBayDataSpots;
string Command = "";
while(Command != "Quit") {
Menu();
cout << "Command: ";
getline(cin, Command);

if(Command == "Report")
RedwoodBayDataSpots.PostSeismicInfo();
}
}
//This function tells the user what he or she can do...
void Menu()
{
cout << "Choices...................................................." << endl;
cout << "-----------------------------------------------------------" << endl;
cout << "\tReport...displays the report." << endl;
cout << "\tQuit.....exits the program." << endl;
cout << "-----------------------------------------------------------" << endl;
}

---

Please post a sample of your input file.

Your code formatting has gotten worse, you need to find an indentation style you like and use it consistently. This will make your code much easier to read and follow your logic.

Also what IDE/compiler are you using?

Jim

The sample line of the file "RedwoodBaySeismicEventList.data" looks like this :

[Text]

Alpha:01232012:0100:2.7

[/Text]

Note:
"Alpha" represents ID
"01232012" represents Date
"0100" represents Hour
"2.7" represents Magnitude

Also, sorry I forgot to indent the code earlier. So, here is the indented code below:

Code:

---


    #include <iostream>
    #include <fstream>
    #include <string>
    #include <vector>
    #include <sstream>
    using namespace std;
   
    //Define a class to represent each Seismic Activity measurement event...
   
        class RedwoodBaySeismicData  {
          string LocationID;  //This is the station that owns this piece of data…
          string Date;    //The date that the values were collected…
          string Time;    //The time of day that the values were collected…
          double SeismicSize;  //Magnitude of Earthquake
         
       
        public:
          RedwoodBaySeismicData();
          RedwoodBaySeismicData(string, string, string, double);
       
          //The first group of member functions are used to change values...
          //Functions are defined in the form of inlines.
       
          void SetID(string ID)    { LocationID = ID; }
          void SetDate(string Day)  { Date = Day; }
          void SetTime(string Hour)  { Time = Hour; }
          void SetSeismicSize(double Magnitude) {SeismicSize = Magnitude; }
         
       
          //The second group allows controlled access to individual value in the class...
       
          string GetID()    { return LocationID; }
          string GetDate()  {return Date; }
          string GetTime()  {return Time; }
          double GetSeismicSize() { return SeismicSize;} 
         
       
       
        };
       
       
       
        //The default constructor sets the private variable members to a harmless value...
       
        RedwoodBaySeismicData::RedwoodBaySeismicData()
        {
        LocationID = "";
        Date = "";
        Time = "";
        SeismicSize = 0.0;
       
        }
       
        //This initializing  constructor allows you to create a object with value already set...
       
        RedwoodBaySeismicData::RedwoodBaySeismicData(string ID, string Day, string Hour, double Magnitude)
        {
        LocationID = ID;
        Date = Day;
        Time = Hour;
        SeismicSize = Magnitude;
       
        }
   
        class RedwoodBayDataList  {
        vector<RedwoodBaySeismicData> RedwoodBayDataSpots;  //Create a collection of location information...
            string FileName ;
        public:
        RedwoodBayDataList()  {FileName = "RedwoodBaySeismicEventList.data";}
       
           
        void PostSeismicInfo();
           
        };
       
   
   
        //Allow the user to post the values for each location...
   
        void RedwoodBayDataList::PostSeismicInfo()
        {
        int K;
        string Line, ID, Date, Hour;
        double Magnitude;
        fstream InFile("RedwoodBaySeismicEventList.data", ios::in);
        //...then get the values for each location...
        RedwoodBaySeismicData Buffer;
   
            cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
            cout << "\tWeekly Report" << endl;
            cout << "\t===============================================================" << endl;
            cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
            cout << "\t===============================================================" << endl;
   
   
        for(size_t K = 0; K < RedwoodBayDataSpots.size(); ++K)  {
                 
          getline(InFile, Line);
          ID = Line.substr(0,4);
          Date =  Line.substr(6,7);
          Hour = Line.substr(9,3);
          istringstream buf(Line.substr(5,2));
          buf>> Magnitude;
           
          Buffer.SetID(ID);    //Use these values to load the Buffer record...
          Buffer.SetDate(Date);
          Buffer.SetTime(Hour);
          Buffer.SetSeismicSize(Magnitude);
          RedwoodBayDataSpots.push_back(Buffer);
     
       
          RedwoodBayDataSpots[K].SetID(ID);
          RedwoodBayDataSpots[K].SetDate(Date);
          RedwoodBayDataSpots[K].SetTime(Hour);
          RedwoodBayDataSpots[K].SetSeismicSize(Magnitude); 
          cout << "\t" << RedwoodBayDataSpots[K].GetID() << "\t" << RedwoodBayDataSpots[K].GetDate() << "\t" << RedwoodBayDataSpots[K].GetTime() << "\t"  << RedwoodBayDataSpots[K].GetSeismicSize();
          }
          cout << "\t===============================================================\n\n" << endl;
   
   
          }
   
       
   
    //Declare the functions...
   
        void RunIT();
        void Menu();
       
       
        int main()
        {
        RunIT();
        }
   
    //This function implements a simple command processor...
   
        void RunIT()
        {
        RedwoodBayDataList RedwoodBayDataSpots;
        string Command = "";
   
        while(Command != "Quit")  {
          Menu();
          cout << "Command: ";
          getline(cin, Command);
   
          if(Command == "Report")
          RedwoodBayDataSpots.PostSeismicInfo();
        }
        }
   
    //This function tells the user what he or she can do...
   
        void Menu()
        {
        cout << "Choices...................................................." << endl;
        cout << "-----------------------------------------------------------" << endl;
        cout << "\tReport...displays the  report." << endl;
        cout << "\tQuit.....exits the program." << endl;
        cout << "-----------------------------------------------------------" << endl;
        }

---

Please post a small sample of your actual input file, with at least 5 to 10 entries.

Jim

Here is the sample of my actual input file:

[text]

Alpha:01232012:0100:2.7
Alpha:01292012:0100:2.2
Alpha:02022012:0100:2.1
Alpha:02032012:0100:3.5
Alpha:03012012:0100:5.4
Alpha:03042012:0100:5.8
Alpha:03112012:0100:5.7
Alpha:03212012:0100:3.1
Alpha:04052012:0100:2.8
Alpha:04152012:0100:2.6
Alpha:04162012:0100:1.3
Alpha:04182012:0100:3.3
Alpha:04222012:0100:3.7
Alpha:05012012:0100:3.3
Alpha:05012012:0100:4.5
Alpha:05022012:0100:6.1
Alpha:05032012:0100:6.0
Alpha:05112012:0100:5.9
Alpha:05122012:0100:6.4
Alpha:06032012:0100:6.1
Alpha:06142012:0100:5.9
Alpha:06182012:0100:5.8
Alpha:06222012:0100:5.2
Beta:01232012:0100:3.7
Beta:01292012:0100:3.2
Beta:02022012:0100:3.1
Beta:02032012:0100:4.5
Beta:03012012:0100:4.4
Beta:03042012:0100:4.8
Beta:03112012:0100:4.7

[/text]

Thanks

In your PostSeismicInfo() function in the following line:

Code:

---

  for(size_t K = 0; K < RedwoodBayDataSpots.size(); ++K)  {

---

When you first encounter this loop your vector contains zero items so K will be equal to the size, therefore the loop will never execute. Normally when you are reading an input file you use a while() loop and push the data into the vector after you read the line of information.


Also because a std::string is a class to construct an empty instance you don't want to use the assignment operator. For example:

Code:

---

  std::string test = ""; // This is not necessary.
  std::string test;      // This is the proper way to construct an empty string.

---

When you use the assignment operator you cause the compiler to do extra steps, for example calling the copy constructor. And in a class constructor you don't actually need to construct an empty string member because the default constructor for a string is an empty string.


Jim

Hi everyone. As per the advice, I have modified my code again. Now, I am using while loop to read the data from the file. However, my programme is still not running. Whenever I try to run the programme the dialog box appears and says "un.exe" has stopped working. By the way, I am usin DEV C++. Also, here is the modified version of the code:

Code:

---

    #include <iostream>
    #include <fstream>
    #include <string>
    #include <vector>
    #include <sstream>
    using namespace std;
   
    //Define a class to represent each Seismic Activity measurement event...
   
        class RedwoodBaySeismicData 
        {
          string LocationID;  //This is the station that owns this piece of data…
          string Date;    //The date that the values were collected…
          string Time;    //The time of day that the values were collected…
          double SeismicSize;  //Magnitude of Earthquake
         
       
        public:
          RedwoodBaySeismicData();
          RedwoodBaySeismicData(string, string, string, double);
       
          //The first group of member functions are used to change values...
          //Functions are defined in the form of inlines.
       
          void SetID(string ID)    { LocationID = ID; }
          void SetDate(string Day)  { Date = Day; }
          void SetTime(string Hour)  { Time = Hour; }
          void SetSeismicSize(double Magnitude) {SeismicSize = Magnitude; }
         
       
          //The second group allows controlled access to individual value in the class...
       
          string GetID()    { return LocationID; }
          string GetDate()  {return Date; }
          string GetTime()  {return Time; }
          double GetSeismicSize() { return SeismicSize;} 
         
       
       
        };
       
       
       
        //The default constructor sets the private variable members to a harmless value...
       
        RedwoodBaySeismicData::RedwoodBaySeismicData()
        {
        LocationID;
        Date;
        Time;
        SeismicSize = 0.0;
       
        }
       
        //This initializing  constructor allows you to create a object with value already set...
       
        RedwoodBaySeismicData::RedwoodBaySeismicData(string ID, string Day, string Hour, double Magnitude)
        {
        LocationID = ID;
        Date = Day;
        Time = Hour;
        SeismicSize = Magnitude;
       
        }
   
        class RedwoodBayDataList
        {
            vector<RedwoodBaySeismicData> RedwoodBayDataSpots;  //Create a collection of location information...
            string FileName ;
        public:
            RedwoodBayDataList()  {FileName = "RedwoodBaySeismicEventList.data";}
           
               
            void PostSeismicInfo();
           
        };
       
   
   
        //Allow the user to post the values for each location...
   
            void RedwoodBayDataList::PostSeismicInfo()
        {
            int K;
            string Line, ID, Date, Hour;
            double Magnitude;
            fstream InFile("RedwoodBaySeismicEventList.data", ios::in);
            //...then get the values for each location...
            RedwoodBaySeismicData Buffer;
   
            cout << "\n\t=============================================================" << endl;  //This section is the report...it's really all about the formatting...
            cout << "\tWeekly Report" << endl;
            cout << "\t===============================================================" << endl;
            cout << "\tLocation\tDate\tHour\tMagnitude" << endl;
            cout << "\t===============================================================" << endl;
   
           
                     
              while (!InFile.eof())           
                 
        {
              getline(InFile, Line);
              ID = Line.substr(0,4);
              Date =  Line.substr(6,7);
              Hour = Line.substr(9,3);
              istringstream buf(Line.substr(5,2));
              buf>> Magnitude;
           
              Buffer.SetID(ID);    //Use these values to load the Buffer record...
              Buffer.SetDate(Date);
              Buffer.SetTime(Hour);
              Buffer.SetSeismicSize(Magnitude);
              RedwoodBayDataSpots.push_back(Buffer);
     
              for(K = 0 ; K < RedwoodBayDataSpots.size(); ++K) 
              {
              RedwoodBayDataSpots[K].SetID(ID);
              RedwoodBayDataSpots[K].SetDate(Date);
              RedwoodBayDataSpots[K].SetTime(Hour);
              RedwoodBayDataSpots[K].SetSeismicSize(Magnitude); 
              cout << "\t" << RedwoodBayDataSpots[K].GetID() << "\t" << RedwoodBayDataSpots[K].GetDate() << "\t" << RedwoodBayDataSpots[K].GetTime() << "\t"  << RedwoodBayDataSpots[K].GetSeismicSize();
              }
              cout << "\t===============================================================\n\n" << endl;
              }
              InFile.close();
   
   
          }
       
   
    //Declare the functions...
   
          void RunIT();
          void Menu();
       
     
          int main()
          {
          RunIT();
          }
   
    //This function implements a simple command processor...
   
          void RunIT()
          {
          RedwoodBayDataList RedwoodBayDataSpots;
          string Command;
   
          while(Command != "Quit")  {
          Menu();
          cout << "Command: ";
          getline(cin, Command);
   
          if(Command == "Report")
          RedwoodBayDataSpots.PostSeismicInfo();
          }
          }
   
    //This function tells the user what he or she can do...
   
          void Menu()
          {
          cout << "Choices...................................................." << endl;
          cout << "-----------------------------------------------------------" << endl;
          cout << "\tReport...displays the  report." << endl;
          cout << "\tQuit.....exits the program." << endl;
          cout << "-----------------------------------------------------------" << endl;
          }

---

As always, I would greatly appreciate any suggestions.

First since you are getting a segmentation fault, have you run the program through your debugger? The debugger will tell you exactly where the problem is detected, and you can view the variables at the time of the crash to help determine the cause of the crash.

My first suggestion is to insure your file is opening correctly. Next you should check the FAQ for information as to why you should not use eof() to control an input loop. I recommend using getline() for controlling the loop:

Code:

---

while(getline(inputFile, string))

---

Where inputFile is your file stream instance and string is a "buffer" for processing the line. The above code will extract one line at time from a file until the end of file. If the getline() fails for any reason then the loop will end.

I also think you should think about starting your file reading function again. First read one line from the file and verify that you have indeed read the file correctly. Then after you insure you are reading one line correctly use a istringstream to parse this line. Think about using getline() with the optional third parameter to extract your Id, date, and time using the colon as the delimiter. Lastly use the extraction operator>> to extract the magnitude value. Verify that you have indeed extracted each item correctly before you move to the next extraction operation. Once you have successfully extracted one line into individual strings and doubles you can then create an instance of your class to insert into your vector.

Jim