C++ test practice

 C++ Objectpooling

#include <string>
#include <iostream>
#include <list>
class Resource
{
    int m_value;
public:
    Resource(){m_value=0;}
    void reset(){m_value=0;}
    int getValue(){return m_value;}
    void setValue(int i){m_value=i;}
};
class ObjectPool
{
    std::list<Resource*> m_resources;
    static ObjectPool* instance;
    ObjectPool(){};
public:
    static ObjectPool* getInstance()
    {
        if(instance = 0)
        {
            instance = new ObjectPool;
        }
        return instance;
    }
    Resource* getResource()
    {
        if(m_resources.empty())
        {
            return new Resource;
        }else{
            Resource* reosurce = m_resources.front();
            m_resources.pop_front();
            return reosurce;
        }
    }
    void returnResource(Resource* object)
    {
        object->reset();
        m_resources.push_back(object);
    }
};
ObjectPool* ObjectPool::instance = 0;
int main()
{
    ObjectPool* pool = ObjectPool::getInstance();
    Resource* one;
    Resource* two;
    one = pool->getResource();
    two = pool->getResource();
    one->setValue(213);
    two->setValue(11);
    std::cout<<one->getValue()<<","<<one<<std::endl;
    std::cout<<two->getValue()<<","<<two<<std::endl;
    pool->returnResource(one);
    pool->returnResource(two);
}

Customer data

#include <iostream>
#include <string>
using namespace std;
struct cdata{
public:
    string name;
    int number;
};
const int NAME_LEN = 10;
const int MAX_CUS_NUM = 20;
enum State {ADD = 1, GET, EXIT};
class CustomerInfo
{
private:
    int m_cusNum = 0;
    cdata m_cdata[MAX_CUS_NUM];
public:
    CustomerInfo() {}
    ~CustomerInfo() { delete[] m_cdata; cout<<"Customer info destroyed"<<endl; }
    int GetNumber(string ID)
    {
        for(int i = 0; i < m_cusNum; i++)
        {
            if(m_cdata[i].name == ID)
            {
                return m_cdata[i].number;
            }
        }
        //return null;
    }
    CustomerInfo& Add(string ID, int num) 
    { 
        m_cdata[m_cusNum].name = ID;
        m_cdata[m_cusNum].number = num;
        m_cusNum++;
        return *this;
    }
    void AddCustomer(string ID, int num)
    {
        m_cdata[m_cusNum].name = ID;
        m_cdata[m_cusNum].number = num;
        m_cusNum++;
    }
};
void ShowMenu()
{
    cout<<"___Menu___"<<endl;
    cout<<"1.Add Customer"<<endl;
    cout<<"2.Get Customer Number"<<endl;
    cout<<"3.Exit"<<endl;
    cout<<endl;
}
void AddCustomer(CustomerInfo * (&cusInfo))
{
    string ID;
    int i; 
    cout<<"[ADD CUSTOMER]"<<endl;
    cout<<"ID : ";
    cin>>ID;
    cout<<"Number : ";
    cin>>i;
    cusInfo->AddCustomer(ID,i);
}
void GetNumber(CustomerInfo * (&cusInfo))
{
    string ID;
    cout<<"[GET NUMBER]";
    cout<<"ID : ";
    cin>>ID;
    cout<<"Number is : "<<cusInfo->GetNumber(ID)<<endl;
}
int main(void)
{
    int choice = 0;
    //CustomerInfo customerInfo;
    //CustomerInfo &_customerInfo = customerInfo;
    CustomerInfo * pCustomerInfo = new CustomerInfo();
    while(1)
    {
        ShowMenu();
        cout<<"Select : ";
        cin>>choice;
        switch(choice)
        {
            case ADD:
            AddCustomer(pCustomerInfo);
            //AddCustomer(&_customerInfo);
            break;
            case GET:
            GetNumber(pCustomerInfo);
            //GetNumber(&_customerInfo);
            break;
            case EXIT:
                delete pCustomerInfo;
                return 0;
        }
    }
    system("pause");
    return 0;
}

mallocFree.cs

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
    int arr[4] = {4,3,2,1};
    int* pArr;
    //set int type size * 4 memory
    pArr = (int *)malloc(sizeof(int) * 4);
    if(pArr == NULL)
    {
        printf("malloc error");
    }
    for (int i =0; i<4; i++)
    {
        pArr[i] = arr[i];
    }
    for (int i =0; i<4; i++)
    {
        printf("%d \n", pArr[i]);
    }
    free(pArr);
    return 0;
}

Swap pointer.cs

#include <iostream>
using namespace std;
void SwapByRef(int *val1, int *val2)
{
    int temp = *val1;
    *val1 = *val2;
    *val2 = temp;
}
void SwapByRef2(int & val1, int &val2)
{
    int temp = val1;
    val1 = val2;
    val2 = temp;
}
//Get pointer of the reference
void SwapPointerByRef(int *(&val1), int * (&val2))
{
    int * temp = val1;
    val1 = val2;
    val2 = temp;
}
//const strict value change 
void CopyPointerValByRef(int * const(&from), int * (&to))
{
    to = from;
}
void CopyValByRef(const int &from, int &to)
{
    to = from;
}
int main(void)
{
    int a = 10;
    int b = 20;
    SwapByRef(&a, &b);
    cout<<"a : "<<a<<" ,b: "<<b<<endl;
    SwapByRef2(a,b);
    cout<<"a : "<<a<<" ,b: "<<b<<endl;
    int num1 = 5;
    int *ptr1 = &num1;
    int num2 = 10;
    int *ptr2 = &num2;
    cout << ptr1 << ","<<ptr2;
    cout<<endl;
    SwapPointerByRef(ptr1, ptr2);
    cout << ptr1 << ","<<ptr2;
    cout<<endl;
    //CopyValByRef(*ptr1, *ptr2);
    CopyPointerValByRef(ptr1, ptr2);
    cout << ptr1 << ","<<ptr2<<endl;     
    cout << *ptr1 << ","<<*ptr2;   
}

Reference Return.cs

#include <iostream>
using namespace std;
//return reference
int & RefRetFunction(int & ref)
{
    ref ++;
    return ref;
}
int literalAdd(const int &val1, const int &val2)
{
    return val1+val2;
}
int main(void)
{
    //num1 & num2 exist
    int num1 = 1;
    int &num2 = RefRetFunction(num1);
    //pointing same adress
    num1 += 2;
    num2 += 4;
    cout<<"num1 : "<<num1<<", num2 : "<<num2<<endl;
    //not pointing reference put only value
    int num3 = 1;
    int num4 = RefRetFunction(num3);
    num3 +=10;
    num4 +=100;
    cout<<"num3 : "<<num3<<", num4 : "<<num4<<endl;
    //temporal memory set
    const int num5 = 40;
    cout<<"literal add : "<<literalAdd(10,20)<<endl;
    return 0;
}