Which of the following function declaration is/are incorrect?

#include<iostream.h> 
class PowerFinder
{
    public:
    void Power(int x = 1, int y = 1)
    {
        int P = 1, i = 1;
        while(++i <= y)
        {
            P *= x;
        }
        cout<< P << endl; 
    } 
};
int main()
{
    PowerFinder FP; 
    FP.Power(2, 6); 
    return 0;
}

#include<iostream.h> 
class BaseCounter
{
    protected:
    long int count;

    public:
    void CountIt(int x, int y = 10, int z = 20)
    {
        count = 0;
        cout<< x << " " << y << " " << z << endl;
    } 
    BaseCounter()
    {
        count = 0;
    }
    BaseCounter(int x)
    {
        count = x ;
    } 
}; 
class DerivedCounter: public BaseCounter
{
    public:
    DerivedCounter()
    { }
    DerivedCounter(int x): BaseCounter(x) 
    { }
};
int main()
{
    DerivedCounter objDC(30); 
    objDC.CountIt(40, 50); 
    return 0; 
}

#include<iostream.h> 
class CuriousTab
{
    static int x; 
    public:
    static void SetData(int xx)
    {
        this->x = xx; 
    }
    static void Display() 
    {
        cout<< x ;
    }
};
int CuriousTab::x = 0; 
int main()
{
    CuriousTab::SetData(22);
    CuriousTab::Display();
    return 0; 
}

#include<iostream.h> 
struct MyStructure
{
    class MyClass
    {
        public:
        void Display(int x, float y = 97.50, char ch = 'a')
        {
            cout<< x << " " << y << " " << ch;
        }
    }Cls; 
}Struc;
 
int main()
{
    Struc.Cls.Display(12, 'b');
    return 0; 
}

#include<iostream.h> 
class CuriousTab
{
    int x, y, z; 
    public:
    void Apply(int xx = 12, int yy = 21, int zz = 9)
    {
        x = xx;
        y = yy += 10;
        z = x -= 2;
    }
    void Display(void)
    {
        cout<< x << " " << y << endl; 
    } 
    void SetValue(int xx, int yy)
    {
        Apply(xx, 0, yy);
    }
};
int main()
{
    CuriousTab *pCuriousTab= new CuriousTab;
   (*pCuriousTab).SetValue(12, 20);
    pCuriousTab->Display();
    delete pCuriousTab;
    return 0; 
}

#include<iostream.h> 
class CuriousTab
{
    int K; 
    public:
    void CuriousTabFunction(float, int , char);
    void CuriousTabFunction(float, char, char);
    
};
int main()
{
    CuriousTab objIB;
    objIB.CuriousTabFunction(15.09, 'A', char('A' + 'A'));
    return 0;
}
void CuriousTab::CuriousTabFunction(float, char y, char z)
{
    K = int(z);
    K = int(y);
    K = y + z;
    cout<< "K = " << K << endl; 
}

#include<iostream.h>
int CuriousTabTest(int x, int y);
int CuriousTabTest(int x, int y, int z = 5);
int main()
{
    cout<< CuriousTabTest(2, 4) << endl; 
    return 0;
}
int CuriousTabTest(int x, int y)
{
    return x * y;
}
int CuriousTabTest(int x, int y, int z = 5)
{
    return x * y * z; 
}

#include<iostream.h> 
struct CuriousTab
{
    int arr[5]; 
    public:
    void CuriousTabFunction(void);
    void Display(void);
};
void CuriousTab::Display(void)
{
    for(int i = 0; i < 5; i++) 
        cout<< arr[i] << " " ;
}
void CuriousTab::CuriousTabFunction(void)
{
    static int i = 0, j = 4; 
    int tmp = arr[i]; 
    arr[i]  = arr[j]; 
    arr[j]  = tmp   ; 
    i++;
    j--;
    if(j != i) CuriousTabFunction();
}
int main()
{
    CuriousTab objCuriousTab = {{ 5, 6, 3, 9, 0 }};
    objCuriousTab.CuriousTabFunction();
    objCuriousTab.Display();
    return 0; 
}

#include<iostream.h> 
class CuriousTabSample
{
    private:
    int AdditionOne(int x, int y = 1) 
    {
        return x * y;
    }
     
    public:
    int AdditionTwo(int x, int y = 1)
    {
        return x / y;
    } 
}; 
int main()
{
    CuriousTabSample objCuriousTab;
    cout<<objCuriousTab.AdditionOne(4, 8)<<" "; 
    cout<<objCuriousTab.AdditionTwo(8, 8); 
    return 0;
}

#include<iostream.h>
#include<string.h> 
class CuriousTabString
{
    char x[50]; 
    char y[50]; 
    char z[50]; 
    public:
    CuriousTabString()
    { }
    CuriousTabString(char* xx)
    {
        strcpy(x, xx); 
        strcpy(y, xx);
    }
    CuriousTabString(char *xx, char *yy = " C++", char *zz = " Programming!")
    {
        strcpy(z, xx); 
        strcat(z, yy); 
        strcat(z, zz);
    } 
    void Display(void)
    {
    cout<< z << endl;
    } 
}; 
int main()
{
    CuriousTabString objStr("Learn", " Java");
    objStr.Display();
    return 0; 
}