STL list::sort() sorting structs

I've got some code as follows:

Code:

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struct Sector
{
    string strName;
    long lPosition;
}

list<Sector> lstSector;

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I want to be able to use the list::sort() member function to sort the list by the strName member but I don't know enough about STL to do this. If I create a list<string> linked-list I can simply call the list::sort function without parameters and it will know how to sort by using the string comparison operators. However, since I'm using a struct in the linked-list I think I need to create a predicate or something to pass as a parameter. Anyone experienced enough with this to help me out?

Also, I am intrigued by everything in the STL that I may be missing out on. I'm thinking of buying a C++ Standard Library book by Nicolai Josuttis(?). Does anyone have this book and can they tell me if its good?

i asked a similar question a week or two ago. i think you need to overload the '<' and '>' operators, so that any comparison between the two is really comparing the strings. nope, i haven't read the book.

I've finally figured it out, I had to make some significant modifications to the struct I had declared to provide it with some boolean operators (>,<,==,etc) and also add in some constructors for the struct. I also changed the way I was calling the list:: push_back function. Then it was a simple matter to call the default list::sort member function with no arguments. Here is some code.

My new struct:

Code:

---

struct Sector
{
    string strName;                        // TSV Sector Name
    long lPosition;                        // Address in input file
    Sector(const Sector& elem) : strName(elem.strName),
                        lPosition(elem.lPosition)
    {
    };
    Sector(const string& name, const long position) : strName(name),
                                            lPosition(position)
    {
    };
    Sector& operator= (const Sector& elem)
    {
        strName = elem.strName;
        lPosition = elem.lPosition;
    };
    bool operator< (const Sector& elem) const
    {
        return strName < elem.strName;
    };
    bool operator> (const Sector& elem) const
    {
        return strName > elem.strName;
    };
    bool operator== (const Sector& elem) const
    {
        return strName == elem.strName;
    };
};

list<Sector> lstSectors;                // Linked-list of "Sector" objects

---

And the code that adds the stuff to the list:

Code:

---

    int iCount = 0;
    string strTemp;
    long lPosition;
    ifstream input("TsvData.Dat");
       
    // Read through the input file and insert data into the struct/list. ////

    input >> strTemp;
    while( !input.eof() )
    {
        // Is this a TSV Sector/SubSector. //////////////////////////////////

        if( strTemp[0] == '.' )
        {
            // Initialize file position from start of "strTemp". /////////////

            lPosition = input.tellg() - (long) strTemp.length();

            // Add "Sector" to linked list and increment count. ///////////////

            lstSectors.push_back( Sector(strTemp,lPosition) );
            iCount++;
        }

        // Output a dot '.' every 100 records. //////////////////////////////

        if( iCount % 100 == 0 )
        {
            cerr << '.';
            cerr.flush();
        }

        // Get the next line of data from the file and continue with the loop.

        input >> strTemp;

    }  // End of "while" loop.

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The above loads the list and will be unsorted in terms of the strName data member. The code to sort the linked-list of structs by the strName member is now simply this:

Code:

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    lstSectors.sort();

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Lastly a snippet of data from a file where I dumped the sorted info to show that it was indeed sorted by the string member and not the order that the data was read in:

Code:

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Name: .ZSE4201M1 Position: 10680
Name: .ZSE4202M1 Position: 10379
Name: .ZSE4601M1 Position: 9998
Name: .ZSE4701M1 Position: 9495
Name: .ZSE4801M1 Position: 9276
Name: .ZSE9001M1 Position: 8465
Name: .ZSEEU01M1 Position: 6588
Name: .ZSEMF01M1 Position: 7160
Name: .ZSEMW01M1 Position: 7528
Name: .ZSENU01M1 Position: 5340
Name: .ZSENU01M2 Position: 5960
Name: .ZSEPD01M1 Position: 0
Name: .ZSEPD01M2 Position: 688
Name: .ZSEPD01M3 Position: 1370

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ygfperson, maybe this can help you if you haven't figured out the answer to that question you asked last week.