Defining a class and calling its member functions

Question

I'm having an issue writing my first function call from a class. First, I'm having trouble using a string array as a parameter in my Unio and Intersect function definitions in the header file. I know arrays have to be passed to functions by reference but I don't see how I'm causing a problem. I've seen it done in examples this way.

Second, the sets I'm creating in the Unio and Intersect functions won't accept the arrays I'm passing as arguments. I imagine it has something to do with not being able to declare anything in the header file but I don't see an alternative to the way I'm passing the arrays into the sets.

Third, I'm trying to call two functions: Unio() and Intersect() in int main() but it's saying they are both undefined. I know I need Class::Function or Object.Function, but the both the Unio and Intersect functions are not attached to objects and when I attach them to their class, Union::Unio or Intersection::Intersect, I'm told "A nonstatic member reference must be relative to a specific object."

#include <string>
#include <cstring>
#include <set>
#include <iostream>
#include <iterator>


#ifndef UNIONSET
#define UNIONSET

class Union
{
    public:
        void Unio(int capture, int capture2, string str1[], string str2[]);

    private:
        int g, i, h;
        string last[100];
        set<string> newset1(last, last+100);
        set<string>::iterator it;

};

#endif

#ifndef INTERSET
#define INTERSET

class Intersection
{
public:
    void Intersect(string str3[], string str4[]);

private:
    set<string> newset2(str3, str3+100);
    set<string> newset3(str4, str4+100);
    set<string>::iterator it2;
};

#endif
<code>

/*
    Andrew_Spiteri_hw3 is an attempt at the third homework assignment for CSE 232.
    This program is designed to test two sets for union and intersection between them and
    subsquently display the results.
*/

#include <string>
#include <iostream>
#include <set>
#include <cstring>
#include <iterator>
#include "Set.h"
using namespace std;

void Union::Unio(int capture2, int capture, string str1[], string str2[])
{
    int g = 0;

    string last[100];
    for(int i = 0; i < capture; ++i)
    {
        for(int h = 0; h < capture2; ++h)
        {
            if(str1[i] == str2[h])
            {
                last[g] = str1[i];
                ++g;
            }
        }       
    }
    set<string> newset1(last, last+100);
    set<string>::iterator it;
    cout<<"The numbers constitute the intersection between the sets.\n";
    for(it=newset1.begin(); it!=newset1.end(); ++it)
    {
        cout << *it<<' ';
    }   
    cout<<'\n';
};

void Intersection::Intersect(string str3[], string str4[])
{
    set<string> newset2(str3, str3+100);
    set<string> newset3(str4, str4+100);
    newset2.insert(newset3.begin(), newset3.end());
    set<string>::iterator it2;
    cout<<"This set constitutes a union between the two sets."<<'\n';
    for(it2=newset2.begin(); it2!=newset2.end(); ++it2)
    {
        cout << *it2<<' ';
    }   
    cout<<'\n';
};

int main()
{
    string set1, set2;
    string extra1[100], extra2[100];
    cout<<"Enter your first set."<<'\n';
    getline(cin,set1);
    char *ch1 = new char[100];
    strcpy(ch1, set1.c_str());
    cout<<"Enter you second set."<<'\n';
    getline(cin,set2);
    char *ch2 = new char[100];
    strcpy(ch2, set2.c_str());
    int z = 0;


    for(int i = 0; i < set1.size(); ++i)
    {
        const char c = ch1[i];
        if(c == ' ')
        {
            ++z;
            continue;
        }
        else if (c == ',')
        {
            continue;
        }
        else if (c >= '0' && c <= '9')
        {
            extra1[z] += ch1[i];    

        }
        else
            continue;
    }   

    int capture = z + 1;
    int r = 0;

    for(int i = 0; i < set2.size(); ++i)
    {
        const char c = ch2[i];
        if(c == ' ')
        {
            ++r;
            continue;
        }
        else if (c == ',')
        {
            continue;
        }
        else if (c >= '0' && c <= '9')
        {
            extra2[r] += ch2[i];    

        }
        else
            continue;
    }   

    int capture2 = r + 1;
    Unio(capture, capture2, &extra1, &extra2);
    Intersect(&extra1, &extra2);
}

Here are the errors I'm getting if anyone is interested.

After adding using namespace std; to the header file I'm getting a lot fewer error messages.

This is what's left.

c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\set.h(21): error C2061: syntax error : identifier 'last'
c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\set.h(37): error C2061: syntax error : identifier 'str3'
c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\set.h(38): error C2061: syntax error : identifier 'str4'
c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\intset.cpp(74): warning C4018: '<' : signed/unsigned mismatch
c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\intset.cpp(98): warning C4018: '<' : signed/unsigned mismatch
c:\users\andrew\documents\visual studio 2012\projects\andrew_spiteri_hw3\andrew_spiteri_hw3\intset.cpp(120): error C2664: 'Union::Unio' : cannot convert parameter 3 from 'std::string (*)[100]' to 'std::string []'

Answer 1

For standard names declared in namespace std you have to specify prefix std:: before them.

So instead of string you have to write std::string, before map you have to write std::map

Or you can include directive in your header where you defined classes

using namespace std;

instead of specifying qualified names.

Or you can introduce each standard name in the global namespace. For example

using std::string;

and so on.

Answer 2

you can initialize obj int class definition, it should be in constructor.

set newset1(last, last+100);

and variable scope of str3,str4

set newset2(str3, str3+100); set newset3(str4, str4+100);

Answer 3

I see the following problems with your code:

1. I don't know what's the purpose of #include "Set.h". Your code does not seem to be using anything from it.
2. You need to move using namespace std; up, before the line #ifndef UNIONSET.
3. Make Union::Unio a static member function.
4. Remove or comment out the line set newset1(last, last+100); from Union. It seems like you don't need any of the member data of the class. However, the other lines don't create compiler errors.
5. Make Intersection::Intersect a static member function.
6. Remove or comment out the lines set newset2(str3, str3+100); and set newset3(str4, str4+100); from Intersection.

7. Change the call to Union::Unio. It needs to be:

   Union::Unio(capture, capture2, extra1, extra2);

8. Change the call to Intersection::Intersect. It needs to be:

   Intersection::Intersect(extra1, extra2);

With the above changes, I was able to compile the file. I didn't check whether the logic in Union::Unio and Intersection::Intersect is correct.