Basic Concept Statement on CPP

In this term, you're supposed to explain each concept provide. 20 problems are provided, with 1 points each.(Total: 20 score)

Initializing Principle

Explain basic principle when initialize a data object.

Memory leak

Explain What is called memory leak.

Function declaration

What is called the declaration of a function?

Continue in loop

What is the use of continue in loop?

What is a pointer?

What is scope?

Reference initialization

void bubble_sort(vector<int>& vec, ofstream* ofilptr = 0)
{
// ......
    if (ofilptr)
        (*ofilptr) << "about to call swap! ix: " << ix << " jx: " << jx
        << "\t swapping: " << vec[ix] << " with " << vec[jx]
    << endl; // debugging output
// ......
}

What is called function overload

What dose sentinel mean in this example?

template <typename elemType>
elemType* find(const elemType* ptr, const elemType* sentinel,
const elemType& value)
{
    while (ptr != sentinel)
    { 
        if (*ptr == value)
            return ptr;
        ptr++; 
    }
    return 0;
}

What is called iterater?

Vector Property

Why can we access the i-th element in a vector(or an array) using *(address_of_the_first_elem+i)?

What is the use of end() in containers?

What is a constructor?

What is a copy constructor?

What's the usage of the destructor?

Tell the difference between the shallow copy and deep copy.

Tell what is public inheritance.

Tell the usage of keyword mutable

Stack memory

One day, Li Hua write a function:

vector<int>& febon(int pos){
    vector<int> v;
    //...
    return v;
}

He find the function cannot run successfully. Tell the reason of the problem.

vector<int> febon(int pos){
    vector<int> v;
    //...
    return v;
}

What is a static member variable?

Simple Coding

In this quotes, giving 10 problems(2 pits each), fix the code block.

Swap by Pointers

Impliment a function below, to swap the values of the space the pointers pointing.

void swap(int *a, int *b){
    //Write down your code.

}

void swap(int *a, int *b){
    //Write down your code.
    int c = *a;
    *a = *b;
    *b = c;
}

Print an Array

An array (int type), with length size as parameter. Print it like: elem1 elem2 ...

void printArary(int*array, int size){
    for(uint32_t i=0; i < size; ++i){
        //write down your code.
        
    }
    cout << endl;
}

void printArary(int*array, int size){
    for(uint32_t i=0; i < size; ++i){
        //write down your code.
        cout << *(array+i) <<" ";
    }
    cout << endl;
}
        

Fix a Destructor

When the instance MyClass is to be distroied, we need to delete all the instances in the class. Fix the destructor in this example.

struct Entity{
    int x;
    int y;
    int z;
    Entity():x(0),y(0),z(0){}
};
class ScopedPtr{
    Entity*e;
    MyClass(Entity*e){
        this->e = e;
    }
    ~ScopedPtr(){
        //Write down your code.

    } 
};

struct Entity{
    int x;
    int y;
    int z;
    Entity():x(0),y(0),z(0){}
};
class ScopedPtr{
    Entity*e;
    MyClass(Entity*e){
        this->e = e;
    }
    ~ScopedPtr(){
        //Write down your code.
        delete e;
    } 
};
    

Const and mutable

In class Triangular, I hope a variable named m_next whose type is int to be modified in const member functions. Declare it.

class Triangular {
public:
    //write down your code.

};

class Triangular {
public:
    //write down your code.
    mutable int m_next; // non-essential
};

Initialize a Float

Initialize 1.3 as a float.

float a;
//assign a as a float.
//Write down your code.

float a;
//assign a as a float.
//Write down your code.
a = 1.3f;

Member function outside a class

In class Stack, here is a menber finction:

class Stack{
    bool empty(){
        return m_stack.empty();
    }
}

Li Hua want to split into a header file and a cpp file, and this is his header file.

class Stack{
    bool empty();
}

try to help him fdesign his cpp file. Hint: define a member function outside the class body

//write down your code.

inline bool Stack::empty()// bool Stack::empty() is also ok.
{ 
    return m_stack.empty(); 
}

Design a pure virtual function.

Design int elem(int pos) const (a member function of class NumSeq) as a pure virtual funciton

class numSeq{
public:
    //write down your code.
}

class numSeq{
public:
    //write down your code.
    virtual int elem(int pos) const = 0;
}

Type define

In this scope, I'd like to use demical to represent double. use typedef to help me.

//write down your code.

//write down your code.
typedef double demical;

Overload operator

Two Triangular iterator class objects are equal if the two m_index are equal, fix the scope.

bool ???(const Triangular_iterator& rhs) const{
    return this->m_index == rhs.m_index;
}

bool operator==(const Triangular_iterator& rhs) const{
    return this->m_index == rhs.m_index;
}

Pass array name

I want to find the pointer of element whose value is 3 and store the address in variable p, using function find as follow. Fix it.

template <typename elemType>
elemType* find(const elemType* ptr, int size, const elemType& value)
{
    for (int ix = 0; ix < size; ++ix)
        if (ptr[ix] == value)
            return &ptr[ix];
    return 0;
}

int main(){
    int* arr = {2,3,5,10};
    //write down your code.
    int* p = ???
}

Realistic Problem

Given 2 problems realistic, you're supposed to get correct codes.

I don't know how to test...

Febonacci

For a sequence 1,2,3,5,8, let febo(x) return the $x_{th}$ febonacci value. Write down your code.

Hint: febo(x) = febo(x-1)+febo(x-2), with febon(1) = 1 and febon(2) = 2 here.

int febon(int x){
    //write down your code.
    vector<int> elems();
    elems.push_back(1);
    elems.push_back(2);
    for(int i = 2; i < x; ++i){
        elems.push_back(elems[i-1]+elems[i-2]);
    }
    return elems[i-1];
}

Inheritance and polimorphism

Gu Gu Gu