Unhandled exception operator overloading - c++

Question

I am practicing with operator overloading and have built a simple calculator.
template <class one> class calc {
int a;
public:
calc() : a(0) {};
calc(const calc& other) : a(other.a) {}
void print() { cout << a; }
calc& operator += (const calc& other);
calc& operator += (const one& i);
calc& operator -= (const calc& other);
calc& operator -= (const one& i);
calc& operator *= (const calc& other);
calc& operator *= (const one& i);
calc& operator /= (const calc& other);
calc& operator /= (const one& i);
const calc& operator - () const;
friend const calc operator + (const calc& our, const calc& other);
friend const calc operator + (const one& i, const calc& other);
friend const calc operator + (const calc& our, const one& i);
};
But unfortunately, when I try to implement the class, it throws the exception:
Unhandled exception at 0x010154C9 in Proctical programming c++
overloading 1.exe: 0xC00000FD: Stack overflow (parameters: 0x00000001,
0x00192F64).
Here is the main:
int main() {
calc <int> one;
one += 2;
one.print();
cin.get();
}
And the problem occurs, for example, here but consequently also in other operators:
template <class one>
calc<one>& calc <one> :: operator += (const one& i) {
*this += i;
return *this;
}
Could you, please, hint me at what I am doing wrong?

Answer 1

Your function calls itself recursively with no condition to exit:
template <class one>
calc<one>& calc <one> :: operator += (const one& i) {
*this += i;
// ^calls the function youre currently in.
return *this;
}
You need to adjust your += operator to use the + operator that you've defined, or as #PaulMcKenzie stated, do the actual addition in += and have + use +=. For example,
template <class one>
calc<one>& calc <one> :: operator += (const one& i) {
a += i;
return *this;
}
seems to work.
You can see a warning about this if your warning level is high enough:
Warning 1 warning C4717: 'calc::operator+=' : recursive on all control paths, function will cause runtime stack overflow
That being said, there are some other problems with your code, like int a should be one a and
friend const calc operator + (const calc& our, const calc& other);
should just be a normal + operator instead of a friend.