GK One-Line Question & Answer

What is the output: class A{int x=5; public: void print()const{cout<<x;} void modify(){x=10;}}; const A a; a.print();

What is 'interface segregation' and encapsulation?

What is the output: class A{int x=0; public: int get()const{return x;} void set(int v){if(v>0) x=v;}}; A a; a.set(-5); cout<<a.get();

What is the output: class A{int x; public: A(int v=0):x(v){} int operator+(const A&o)const{return x+o.x;}}; A a(3),b(4); cout<<a+b;

What is 'friend class' in C++?

What is the output: class A{int x; public: A(int v):x(v){} friend ostream& operator<<(ostream& os,const A& a){os<<a.x; return os;}}; A a(99); cout<<a;

What is the purpose of making constructors private?

What is the output: class A{int x=1,y=2; public: int sum()const{return x+y;} void scale(int f){x*=f; y*=f;}}; A a; a.scale(3); cout<<a.sum();

What is 'module' in C++20 related to encapsulation?

What is the output: class A{int x; public: void setX(int v){x=v;} int getX()const{return x;}}; A a; cout<<a.getX();

What is 'cohesion' in OOP?

What is abstraction in C++?

What is the output: class Shape{public: virtual double area()=0;}; class Circle:public Shape{double r; public: Circle(double r):r(r){} double area(){return 3.14*r*r;}}; Shape*s=new Circle(1); printf("%.2f",s->area());

What is an 'interface' in C++ abstraction?

What is the output: class A{public: virtual int f()=0; virtual ~A()=default;}; class B:public A{public: int f(){return 42;}}; A*p=new B; cout<<p->f();

What is 'type erasure' in C++?

What is the output: class A{protected: int x; public: A(int v):x(v){} virtual void show()=0;}; class B:public A{public: B(int v):A(v){} void show(){cout<<x;}}; B b(7); b.show();

What is 'concept' in C++20?

What is the output: class Animal{public: virtual string sound()=0; string describe(){return "I say: "+sound();}}; class Dog:public Animal{public: string sound(){return "Woof";}}; Dog d; cout<<d.describe();

What is 'dependency inversion principle'?

What is the output: template<typename T> T maxVal(T a,T b){return a>b?a:b;} cout<<maxVal(3,7)<<maxVal(2.5,1.5);

What is the output: class Stack{vector<int> v; public: void push(int x){v.push_back(x);} int pop(){int x=v.back();v.pop_back();return x;}}; Stack s; s.push(1); s.push(2); cout<<s.pop();

What is 'generic programming'?

What is 'template specialization' as abstraction?

What is the output: auto square=[](auto x){return x*x;}; cout<<square(3)<<square(2.5);

What is 'std::function' and type erasure?

What is the output: class Shape{public: virtual double perimeter()=0; virtual double area()=0;}; class Rect:public Shape{double w,h; public: Rect(double w,double h):w(w),h(h){} double perimeter(){return 2*(w+h);} double area(){return w*h;}}; Rect r(3,4); cout<<r.area()<<' '<<r.perimeter();

What is 'abstraction layer'?

What is 'std::variant' as abstraction?

What is the output: class Logger{public: virtual void log(string msg)=0;}; class ConsoleLog:public Logger{public: void log(string msg){cout<<msg;}}; Logger*l=new ConsoleLog; l->log("OK");

What is 'template method pattern'?

What is the output: template<int N> struct Factorial{static const int value=N*Factorial<N-1>::value;}; template<> struct Factorial<0>{static const int value=1;}; cout<<Factorial<5>::value;

What is 'std::any' in C++17?

What is 'abstraction vs implementation' tradeoff?

What is the output: class Base{public: void interface(){impl();} private: virtual void impl(){cout<<'B';}}; class Der:public Base{private: void impl()override{cout<<'D';}}; Der d; d.interface();

What is 'non-virtual interface' (NVI) pattern?

What is the output: struct Functor{int x; Functor(int v):x(v){} int operator()(int y){return x+y;}}; Functor f(10); cout<<f(5);

What is 'policy-based design'?

What is the output: class A{public: virtual void f(){cout<<1;}}; void g(A* a){a->f();} class B:public A{public: void f(){cout<<2;}}; g(new B);

What is 'duck typing' concept in C++?