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Error: sortLastNames was not declared in this scope.

mirahmed39 (6)
Hi there,
I have to create a class named book which will read from a file containing the book info and store them into a book array. one of the tasks is to sort the array by author's last name and output the sorted file into another fstream object. I have used the simple bubble sort but I am getting an error something like this:
Error: sortLastNames was not declared in this scope.
YOU WILL SEE THE FUNCTION CALL THIRD LINE AFTER THE FIRST WHILE LOOP. THAT IS WHERE I AM GETTING THE ERROR. (LINE 61)

I have combined everything into one file.
Note: I am able to figure out everything else. It is just this error that giving me hard time.
Thank you in advance. 
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#include<iostream>
#include<string>
#include<fstream>
using namespace std;

class book
{
public:
    book();
    book(string catalog, string lname, string fname, string title, string genre, string available);
    //Accesor Functions
    string getCatalogNumber();
    string getLastName();
    string getFirstName();
    string getBookTitle();
    string getBookGenre();
    string getAvailability();
    //Mutator Functions
    void setCatalogNumber(string catalog);
    void setLastName(string lname);
    void setFirstName(string fname);
    void setBookTitle(string title);
    void setBookGenre(string genre);
    void setAvailability(string available);
    //other member functions
    void sortLastName(book array[], int length);
    void sortGenre(book array[], int length);

private:
    string catalogNumber,
               lastName,
               firstName,
               booktitle,
               bookgenre,
               availability;

};

int main(int argc, char* argv[])
{
    ifstream inputFile1, inputFile2;
    ofstream outputFile1, outputFile2, outputFile3;
    inputFile1.open("input1.txt");
    string catalog, lname, fname, title, genre, available; // placeholder for contents in inputFile1.
    int size = 0;
    book arr[100]; // creating a book array so as to store the objects we extract form the inputFile1.

    while(inputFile1 >> catalog >> lname >> fname >> title >> genre >> available)
    {
        arr[size].setCatalogNumber(catalog);
        arr[size].setLastName(lname);
        arr[size].setFirstName(fname);
        arr[size].setBookTitle(title);
        arr[size].setBookGenre(genre);
        arr[size].setAvailability(available);

        size++;
    }
    inputFile2.close();
    // the following code computes computational tasks 1 and 2.
    sortLastName(arr, size);
    outputFile1.open("output1.txt");
    for(int i = 0; i < size; i++)
    {
        outputFile1 << arr[i].getCatalogNumber() << " " << arr[i].getLastName()
                    << " " << arr[i].getFirstName() << " " << arr[i].getBookTitle()
                    << " " << arr[i].getBookGenre() << " " << arr[i].getAvailability() << endl;
    }
    outputFile1.close();

    sortGenre(arr,size);
    outputFile2.open("output2.txt");
    for(int i = 0; i < size; i++)
    {
        outputFile2 << arr[i].getCatalogNumber() << " " << arr[i].getLastName()
                    << " " << arr[i].getFirstName() << " " << arr[i].getBookTitle()
                    << " " << arr[i].getBookGenre() << " " << arr[i].getAvailability() << endl;
    }
    outputFile2.close();

    // the following code computes the computational task 3.
    inputFile2.open("input2.txt");
    outputFile3.open("output3.txt");
    string requestCatalog;
    bool found;
    while(inputFile2 >> requestCatalog)
    {
        for(int p = 0; p < size; p++)
        {
            if((arr[p].getCatalogNumber() == requestCatalog) && (arr[p].getAvailability() == "available"))
            {
                outputFile3 << requestCatalog << " " << arr[p].getBookTitle() << " available" << endl;
                found = true;
                break;
            }
            else if((arr[p].getCatalogNumber() == requestCatalog) && (arr[p].getAvailability() == "unavailable"))
            {
                outputFile3 << requestCatalog << " " << arr[p].getBookTitle() << " unavailable" << endl;
                found = true;
                break;
            }
            else
                found = false;
        }
        if(!found)
            outputFile3 << requestCatalog << " unavailable" << endl;
    }
    inputFile2.close();
    outputFile3.close();

    return 0;
}

book::book()
{
     string catalogNumber = "",
               lastName = "",
               firstName = "",
               booktitle = "",
               bookgenre = "";
               availability= "";
}

book :: book(string catalog, string fname, string lname, string title, string genre, string available)
{
    catalogNumber = catalog;
    lastName = lname;
    firstName = fname;
    booktitle = title;
    bookgenre = genre;
    availability = available;

}

string book :: getCatalogNumber()
{
    return catalogNumber;
}

string book :: getLastName()
{
    return lastName;
}

string book :: getFirstName()
{
    return firstName;
}

string book :: getBookTitle()
{
    return booktitle;
}

string book :: getBookGenre()
{
    return bookgenre;
}

string book :: getAvailability()
{
    return availability;
}

void book :: setCatalogNumber(string catalog)
{
    catalogNumber = catalog;
}
void book :: setLastName(string lname)
{
    lastName = lname;
}
void book :: setFirstName(string fname)
{
    firstName = fname;
}
void book :: setBookTitle(string title)
{
    booktitle = title;
}
void book :: setBookGenre(string genre)
{
    bookgenre = genre;
}
void book :: setAvailability(string available)
{
    availability = available;
}

void book :: sortLastName(book array[], int length)
{
    for(int i = 0; i < length-1; i++)
    {
        for(int j = i+1; j < length; j++)
        {
            if(array[j].lastName < array[i].lastName)
            {
                string temp = array[i].lastName;
                array[i].lastName = array[j].lastName;
                array[j].lastName = temp;
            }
        }
    }
}

void book :: sortGenre(book array[], int length)
{
    for(int i = 0; i < length-1; i++)
    {
        for(int j = i+1; j < length; j++)
        {
            if(array[j].bookgenre < array[i].bookgenre)
            {
                string temp = array[i].bookgenre;
                array[i].bookgenre = array[j].bookgenre;
                array[j].bookgenre = temp;
            }
        }
    }

}
Last edited on
shadowmouse (539)
sortLastName is a member function, so you have to call it from an instance of book. By the way, why have you made a member function that takes a group of objects to operate on, rather than operating on the object of which it is a member?
mirahmed39 (6)
I see what you mean. But, let me just make sure that I have understood or not.
So, it will be like : bookObject.sortLastName(); ????
By the way, thank you for the reply.
shadowmouse (539)
Any member function has to be called like you said. I would advise that you stop it being a member function as it is not related to the particular instance, as a rule, any function where you have to pass books into the function so as to operate on them, should not be a member function of book, unless it needs access to private/protected variables.
mirahmed39 (6)
I see, let me define it the way you said then.
mirahmed39 (6)
It compiles now, but when I checked the output files, the list is not sorted. 
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#include<iostream>
#include<string>
#include<fstream>
using namespace std;

class book
{
public:
    book();
    book(string catalog, string lname, string fname, string title, string genre, string available);
    //Accesor Functions
    string getCatalogNumber();
    string getLastName();
    string getFirstName();
    string getBookTitle();
    string getBookGenre();
    string getAvailability();
    //Mutator Functions
    void setCatalogNumber(string catalog);
    void setLastName(string lname);
    void setFirstName(string fname);
    void setBookTitle(string title);
    void setBookGenre(string genre);
    void setAvailability(string available);

private:
    string catalogNumber,
               lastName,
               firstName,
               booktitle,
               bookgenre,
               availability;

};

void sortLastName(book array[], int length);
void sortGenre(book array[], int length);


int main(int argc, char* argv[])
{
    ifstream inputFile1, inputFile2;
    ofstream outputFile1, outputFile2, outputFile3;
    inputFile1.open("input1.txt");
    string catalog, lname, fname, title, genre, available; // placeholder for contents in inputFile1.
    int size = 0;
    book arr[100]; // creating a book array so as to store the objects we extract form the inputFile1.

    while(inputFile1 >> catalog >> lname >> fname >> title >> genre >> available)
    {
        arr[size].setCatalogNumber(catalog);
        arr[size].setLastName(lname);
        arr[size].setFirstName(fname);
        arr[size].setBookTitle(title);
        arr[size].setBookGenre(genre);
        arr[size].setAvailability(available);

        size++;
    }
    inputFile2.close();
    // the following code computes computational tasks 1 and 2.
    sortLastName(arr, size);
    outputFile1.open("output1.txt");
    for(int i = 0; i < size; i++)
    {
        outputFile1 << arr[i].getCatalogNumber() << " " << arr[i].getLastName()
                    << " " << arr[i].getFirstName() << " " << arr[i].getBookTitle()
                    << " " << arr[i].getBookGenre() << " " << arr[i].getAvailability() << endl;
    }
    outputFile1.close();

    sortGenre(arr,size);
    outputFile2.open("output2.txt");
    for(int i = 0; i < size; i++)
    {
        outputFile2 << arr[i].getCatalogNumber() << " " << arr[i].getLastName()
                    << " " << arr[i].getFirstName() << " " << arr[i].getBookTitle()
                    << " " << arr[i].getBookGenre() << " " << arr[i].getAvailability() << endl;
    }
    outputFile2.close();

    // the following code computes the computational task 3.
    inputFile2.open("input2.txt");
    outputFile3.open("output3.txt");
    string requestCatalog;
    bool found;
    while(inputFile2 >> requestCatalog)
    {
        for(int p = 0; p < size; p++)
        {
            if((arr[p].getCatalogNumber() == requestCatalog) && (arr[p].getAvailability() == "available"))
            {
                outputFile3 << requestCatalog << " " << arr[p].getBookTitle() << " available" << endl;
                found = true;
                break;
            }
            else if((arr[p].getCatalogNumber() == requestCatalog) && (arr[p].getAvailability() == "unavailable"))
            {
                outputFile3 << requestCatalog << " " << arr[p].getBookTitle() << " unavailable" << endl;
                found = true;
                break;
            }
            else
                found = false;
        }
        if(!found)
            outputFile3 << requestCatalog << " unavailable" << endl;
    }
    inputFile2.close();
    outputFile3.close();

    return 0;
}

book::book()
{
     string catalogNumber = "",
               lastName = "",
               firstName = "",
               booktitle = "",
               bookgenre = "";
               availability= "";
}

book :: book(string catalog, string fname, string lname, string title, string genre, string available)
{
    catalogNumber = catalog;
    lastName = lname;
    firstName = fname;
    booktitle = title;
    bookgenre = genre;
    availability = available;

}

string book :: getCatalogNumber()
{
    return catalogNumber;
}

string book :: getLastName()
{
    return lastName;
}

string book :: getFirstName()
{
    return firstName;
}

string book :: getBookTitle()
{
    return booktitle;
}

string book :: getBookGenre()
{
    return bookgenre;
}

string book :: getAvailability()
{
    return availability;
}

void book :: setCatalogNumber(string catalog)
{
    catalogNumber = catalog;
}
void book :: setLastName(string lname)
{
    lastName = lname;
}
void book :: setFirstName(string fname)
{
    firstName = fname;
}
void book :: setBookTitle(string title)
{
    booktitle = title;
}
void book :: setBookGenre(string genre)
{
    bookgenre = genre;
}
void book :: setAvailability(string available)
{
    availability = available;
}

void sortLastName(book array[], int length)
{
    for(int i = 0; i < length-1; i++)
    {
        for(int j = i+1; j < length; j++)
        {
            if(array[j].getLastName() < array[i].getLastName())
            {
                string temp = array[i].getLastName();
                array[i].getLastName() = array[j].getLastName();
                array[j].getLastName() = temp;
            }
        }
    }
}

void sortGenre(book array[], int length)
{
    for(int i = 0; i < length-1; i++)
    {
        for(int j = i+1; j < length; j++)
        {
            if(array[j].getBookGenre() < array[i].getBookGenre())
            {
                string temp = array[i].getBookGenre();
                array[i].getBookGenre() = array[j].getBookGenre();
                array[j].getBookGenre() = temp;
            }
        }
    }

}
shadowmouse (539)
You are both passing and returning copies so you are not modifying anything permanent. Have a look at passing by reference and make setLastName instead of getLastName() =, because that is setting the value of a copy of lastName.
mirahmed39 (6)
can you please provide an example of how the setLastName should look? And, I thought array is always passed by reference.
Thanks
shadowmouse (539)
No, I'm afraid you have to pass arrays by reference, it isn't automatic. book::setLastname(string newLastName) would look something like this:
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void book::setLastName(string newLastName)
{
lastName = newLastName;
}

If I remember rightly, the syntax for passing arrays by reference is
 
 
void sortGenre(book (&array)[], int length)
mirahmed39 (6)
it worked. I used the mutator functions as you said, but the array did need to pass by reference.
Now, I have run into a big problem. I have separated the header, implementation and main file and it is giving me bunch of errors and they are same:
undefined reference to book::book() and same for all other variables.
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