What went wrong here? Pls help

Question

https://code.sololearn.com/c1wXRcgqxqjg/?ref=app

Answer 1

You have to call cin within the constructor of the class (which you didn't define, and should) to initialize l, b , s, ie:

class area
{
private:
int l,b,s; //data member

public:// access specifier
area(); //constructor
int rectangle(); //member function
int square(); // declaration
};

area::area(){
cin>>l>>b>>s;
}

Answer 2

Adding to what BootInk said.

Although it workes here, I would not recommend performing i/o in class methods ( especially constructor ). You would have a very hard time working with such design.