istream Unhandled exception, stack overflow -

i'm new c++, , trying istream work. have class of:

class rat { private:     int num;     int denom; public:      rat();     rat(const int&, const int&);     rat(const int&);      friend ostream& operator << (ostream&, const rat&);     friend istream& operator >> (istream&, const rat&); }; rat::rat(void) {     num = 0;     denom = 1; }  rat::rat(const int &n, const int &d) {     num = n;     denom = d;     simplify(); }  rat::rat(const int &n) {     num = n;     denom = 1; }  ostream& operator << (ostream &os, const rat &r1) {     os << r1.num;     os << "/";     os << r1.denom;     return os; }  istream& operator >> (istream &is, const rat &r1) {     >> r1.num;     >> r1.denom;     return is; } 

i have .cpp of:

#include <iostream> #include <conio.h> using namespace std; #include "rats.h"  void main() {     rat r1(3,4), r2(2,3), r3;       system("cls");     cout << "please enter rational number: ";     cin >> r3; } 

my problem occurs whenever comes across "is >> r1.num;" line. gives me error: unhandled exception @ 0x772d15de in ratclass.exe: 0xc00000fd: stack overflow.

again, i'm new, have not learned possible cause yet. appreciated.

looks might fact you're accepting const rat &r1 sending data istream changing r1. can't change constants. not sure if issue that's first obvious thing came mind.

try this:

istream& operator >> (istream &is, rat &r1) {     >> r1.num;     >> r1.denom;     return is; } 

don't forget change definition in class:

friend istream& operator >> (istream&, rat&);