Hi, teaching myself C++ and require some help / assistance.

Source Code 1


#include <iostream>
#include <iomanip>
using namespace std;

class Time;

// date class
class Date {
int mo, da, yr;
public:
Date(int m, int d, int y) {mo = m; da = d; yr = y;}
friend void display(const Date&, const Time&); // bridge function
};

// time class
class Time{
int hr, min, sec;
public:
Time (int h, int m, int s) {hr = h; min = m; sec = s;}
friend void display(const Date&, const Time&); // bridge function
};

// a bridge friend function
void display(const Date& dt, const Time& tm)
{
cout << dt.mo << '/' << dt.da << '/' << dt.yr;
cout << ' ';
cout << tm.hr << ':' << tm.min << ':' << setfill('0') << right << setw(2) << tm.sec;
}

int main()
{
Date dt(2, 16, 97);
Time tm(10, 55, 5);
display(dt, tm);
return 0;
}

1st Question:-
I've added the iomanip header and cout manipulators [ setfill('0') << right << setw(2) ] to the orignal source so that the display shows:
2/16/97 10:55:05 instead of 2/16/97 10:55:5

Is this an acceptable way of manipulating the data members or are there better alternatives?


Source Code 2


#include <iostream>
#include <cstring>
using namespace std;

// date class
class Date {
int mo, da, yr;
char *month;
public:
Date(int m = 0, int d = 0, int y = 0);
~Date();
void display() const;
};

Date::Date(int m, int d, int y)
{
static char *mos[] ={ "January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"};

mo = m; da = d; yr = y;
if (m !=0) {
month = new char[strlen(mos[m-1])+1];
strcpy(month, mos[m-1]);
}
else
month = 0;
}

// destructor
Date::~Date()
{
delete[] month;
}

// display member function
void Date::display() const
{
if (month != 0)
cout << month << ' ' << da << ", " << yr;
else
cout << da << ", " << yr;
}

int main()
{
Date dt(5, 24, 2000);
dt.display();
return 0;
}

2nd Question:-
Referring to the Date function in the Date class, I can't understand the following assignment:

month = new char[strlen(mos[m-1])+1];

Since the following assignment will work just fine:

month = new char[strlen(mos[m-1])];

Are there any reasons to assign month the former way?