Operator Overloading solution - c++

Question

i have made a c++ code. An MList that holds items in it. I overloaded the << operator to print the values in MList in a particular format. Here is the code:
friend ostream& operator<<(ostream &out, const MSet<V> &m)
{
string s = "";
s += "Size " + to_string(m.size_) + "\n";//out << m.size() << endl;
s += "Cap " + to_string(m.capacity_) + "\n"; //out << m.capacity() << endl;
for (int i = 0; i < m.size_; i++)
{
if (i < m.size_ - 1)
s += m.ary[i].element + ",";//out << m.ary[i].element << ",";
else
s += m.ary[i].element;
}
//cout << "String : " << s;
return out << s;
}
But it does not print correct value. It prints the size and capacity right but not the values. Instead of values, it prints some signs like heart:
You can see it prints size and capacity right but not the values. Here is the relevant code. I am executing case 2 only right now:
#include<iostream>
using std::cout; using std::endl;
using std::ostream; using std::cin; using std::boolalpha;
#include<string>
using std::string;
using namespace std;
template <class V>
struct SetElement
{
V element;
int cnt;
SetElement() = default;
SetElement(V v) : element(v){}
};
template <class V>
ostream &operator<<(ostream & o,const SetElement<V> &p)
{
return o << p.element;
}
template <class V>
class MSet
{
private:
SetElement<V> *ary;
size_t capacity_;
size_t size_;
public:
MSet(V val)
{
capacity_ = 2;
ary = new SetElement<V>[capacity_];
ary[0].element = val;
ary[0].cnt = 1;
size_ = 1;
}
SetElement<V>* find(V val)
{
SetElement<V> *found = nullptr;
bool yes = false;
for (int i = 0; i < size_ && !yes; i++)
{
if (ary[i].element == val)
{
found = &ary[i];
yes = true;
}
}
return found;
}
friend ostream& operator<<(ostream &out, const MSet<V> &m)
{
string s = "";
s += "Size " + to_string(m.size_) + "\n";//out << m.size() << endl;
s += "Cap " + to_string(m.capacity_) + "\n"; //out << m.capacity() << endl;
for (int i = 0; i < m.size_; i++)
{
if (i < m.size_ - 1)
s += m.ary[i].element + ",";//out << m.ary[i].element << ",";
else
s += m.ary[i].element;
}
//cout << "String : " << s;
return out << s;
}
};
int main(){
int test;
long l1, l2, l3;
cin >> test;
cout << boolalpha;
switch (test){
// ...
case 2: {
cin >> l1 >> l2;
MSet<long> m_l(l1);
auto p = m_l.find(l1);
if (p != nullptr)
cout << *p << endl;
else
cout << "Val:" << l1 << " not found " << endl;
p = m_l.find(l2);
if (p != nullptr)
cout << *p << endl;
else
cout << "Val:" << l2 << " not found " << endl;
//cout << "MList \n";
cout << m_l;
break;
}
// ...
}
}

Answer 1

You're adding the values into a temporary string, which may involve implicit conversions depending of the template type (here your numerical values were converted into characters).
Just print the values, without the temporary string:
friend ostream& operator<<(ostream &out, const MSet<V> &m)
{
out << "Size " << m.size_ << endl;
out << "Cap " << m.capacity_ << endl;
for (int i = 0; i < m.size_; i++)
{
if (i < m.size_ - 1)
out << m.ary[i].element << ",";
else
out << m.ary[i].element;
}
return out;
}