Strange characters when displaying the char array C++ - c++

Question

I can't correctly display information. In the text displayed extra characters. Most likely a problem with the zero character but I was not able to eliminate.
First file: person.h Here I describe a simple class.
#ifndef PERSON_H_INCLUDED
#define PERSON_H_INCLUDED
#include <string>
using std::string;
class Person
{
private:
static const int m_iLIMIT = 25;
string m_sLname; // lastname
char m_cFname[m_iLIMIT]; // firstname
public:
Person () { m_sLname = ""; m_cFname[0] = '\0'; } // #1
Person(const string & sLn, const char * pcFn = "Adam"); // #2
// show lastname и firstname
void Show() const; // format: firstname lastname
void FormalShow() const; // format: lastname, firstname
};
#endif // PERSON_H_INCLUDED
Second file: p_functions.cpp Here I define class methods
#include "person.h"
#include <iostream>
#include <string>
#include <cstring>
using std::string;
using std::cout;
using std::cin;
using std::endl;
// #2
Person::Person(const string & sLn, const char * cFn)
{
m_sLname = sLn;
strcat(m_cFname, cFn);
}
void Person::Show() const
{
cout << "First format: " << m_cFname << ", " << m_sLname << endl;
}
void Person::FormalShow() const
{
cout << "Second format: " << m_sLname << ", " << m_cFname << endl;
}
Third file: main.cpp Here I am testing methods
#include <iostream>
#include "person.h"
using namespace std;
int main()
{
Person one;
Person two("Smith");
Person three("immanuel", "Kant");
one.Show();
one.FormalShow();
two.Show();
two.FormalShow();
three.Show();
three.FormalShow();
return 0;
}
This is the result I get

Answer 1

in the second constructor m_cFname[0] is not initialized with 0
use strcpy instead of strcat
and you will have problem with longer first names