reference member variable

ankushnandan (64)
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#include<iostream>
using namespace std;

class TypeCheck
{
      private:                       
              int var;
              int *varptr;
              const int varconst;
              const int *varptrconst;
              int &ref;              // Here i have doubt
      public:
             TypeCheck(int a): varconst(5),ref(a)
             {
                         cout<<"Do Nothing";
                         }
             
             void print()         // Function to print value of Member variable
             {
                  cout<<"value of var  "<<var<<"\n";
                  cout<<"value of *varptr  "<<*varptr<<"\n";
                  cout<<"value of vvarconstar "<<varconst<<"\n";
                  cout<<"value of varptrconst "<<*varptrconst<<"\n";
                  cout<<"value of ref "<<ref<<"\n";
             }
             
              
              
      };


int main()
{
    int item = 5;
    TypeCheck obj1(item); // Passing item that will be stored in TypeCheck::ref
    obj1.print();
    item = 10;            // Why the value of TypeCheck::ref is not changed?
    obj1.print();
    cin>>item;        
    obj1.print();     //After using "cin",TypeCheck::ref has junk value. why?
    
    cin>>item;
}



Plz read the commets
GFreak45 (105)
its actually a pointer
do something more like:
int *ref;
and replace the TypeCheck(int a): varconst(5), ref(a)
with TypeCheck(int &a): varconst(5), ref(&a)
and the cout<<"value of ref "<<ref<<"\n";
with cout<<"value of ref "<<*ref<<"\n";

the operator & means address of
and a <type> *varName is a pointer to variables of that type which is a 1 byte variable that holds addresses
ie:
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int *x, *y, z = 5;
x = &z; //value of x = address of z, value of *x = value of z
y = x; //value of y = address of z, value of y = value of x;
cout << *x << endl << x << endl << *y << endl << y;
/*
outputs:
address of z
5
address of z
5
*/
*y = 10; //value of z = 10
cout << endl << z; //outputs 10
Last edited on
ankushnandan (64)
Hi GFreak45,

Why cant we have int &ref as member variable?
Peter87 (11254)
You are passing the integer by value to the constructor so a inside the constructor is a copy of item in main. ref binds to a that will no longer exist after the constructor has ended so you end up with an invalid reference. Passing by reference will fix this problem.
Last edited on
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