C -常见英文面试笔试题.doc

文档介绍：C++-常见英文面试笔试题
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What is copy constructor?
Constructor which initializes the it's object member variables ( by shallow copying) with another object of the same class. If you don't implement one in your class then compiler implements one for you.
for example:
Boo Obj1(10); // calling Boo constructor
Boo Obj2(Obj1); // calling boo copy constructor
Boo Obj2 = Obj1;// calling boo copy constructor
When are copy constructors called?
Copy constructors are called in following cases:
a) when a function returns an object of that class by value
b) when the object of that class is passed by value as an argument to a function
c) when you construct an object based on another object of the same class
d) When compiler generates a temporary object
What is assignment operator?
Default assignment operator handles assigning one object to another of the same class. Member to member copy (shallow copy)
What are all the implicit member functions of the class? Or what are all the functions which compiler implements for us if we don't define one.??
default ctor
copy ctor
assignment operator
default destructor
address operator
What is conversion constructor?
constructor with a single argument makes that constructor as conversion ctor and it can be used for type conversion.
for example:
class Boo
{
public:
Boo( int i );
};
Boo BooObject = 10 ; // assigning int 10 Boo object
What is conversion operator??
class can have a public method for specific data type conversions.
for example:
class Boo
{
double value;
public:
Boo(int i )
operator double()
{
return value;
}
};
Boo BooObject;
double i = BooObject; // assigning object to variable i of type double. now conversion operator gets called to assign the value.
What is diff between malloc()/free() and new/delete?
malloc allocates memory for object in heap but doesn't invoke object's constructor to initialli