stri(){}
stri(char *s);//constructor used to initilize object with constant string
stri(stri &s1);//copy constructor performs memberwise copy
friend stri operator+(stri &s1,stri &s2);//conccats two string objects
void operator=(stri &s);//performs memberwise copy
//In main
//s1 and s2 are initilized with constant strings
stri s3=s1+s2; //Gives error? However when copy constructor is removed works fine
C++ Copy Constructor – Why Copy Constructor is Not Invoked
c++
Best Answer
You declared the copy constructor like this:
This line, specifically the expression on the right hand side of
=
, produces a temporary:As this is copy initialization, it needs to call the copy constructor. But as temporaries cannot bind to references to non-const objects, you get an error.
When you comment out the copy constructor, the compiler generates one for you. Its signature is then
Now it takes a reference to const and a temporary can bind to it. The fix should be obvious now.
Note that even though a well formed copy initialization requires an accesible copy constructor, the compiler can choose to elide the call to it during optimization, even when that elision changes the observable behavior of your program.