[Light02]

ok I'm getting three errors in my program and I'm not sure how to fix them I'm gonna copy what I got down in my code to get another opinion.

though I guess some background is in order it's an assignment that has myself creating a class called DayOfTheWeek with three public functions setDay(), getDay() and printDay() now the output needed is the first day inputted and the next day after the first day. the assignment didn't say how to pull this off so I went with a user input method as shown below my first question deals with the errors I mentioned in lines 53, 58, and 69. The second question is such how should I word the if statement

#include <iostream>
#include <string>

using namespace std;

class DayOfTheWeek
{
public:
	void setDay(int);
	void printDay() const;
	void getDay(int&);

private:
	string Sun;
	string Mon;
	string Tues;
	string Wed;
	string Thurs;
	string Fri;
	string Sat;
};

void DayOfTheWeek::setDay(int day)
{
	if(day=1)
		Sun=day;

	else if(day=2)
		Mon=day;

	else if(day=3)
		Tues=day;

	else if(day=4)
		Wed=day;

	else if(day=5)
		Thurs=day;

	else if(day=6)
		Fri=day;

	else if(day=7)
		Sat=day;
}

void DayOfTheWeek::getDay(int day)
{
	return day;
}

void DayOfTheWeek::printDay()
{
	cout << day;
}

int main()
{
	DayOfTheWeek firstDay;
	DayOfTheWeek secondDay;

	int Day = 0;

	Day = firstDay.getDay();

	cout << "Welcome to the Set Day Program" << endl;
	cout << endl;
	cout << "please input what day it is:" << endl;
	cout << "1 = Sun" << endl;
	cout << "2 = Mon" << endl;
	cout << "3 = Tues" << endl;
	cout << "4 = Wed" << endl;
	cout << "5 = Thurs" << endl;
	cout << "6 = Fri" << endl;
	cout << "7 = Sat" << endl;
	cout << "Make your selection here: ";
	cin >> Day;
	cout << endl;

	cout << "Today is "; firstDay.printDay(); cout << endl;

	return 0;
}

[JITHU]

First of all, day is not a local variable in your printDay() nor a member of the DayOfTheWeek class.
That's the cause for the first error.

To getDay(), you need to pass a int variable, which you're not doing it in your main function.

Also it's better if you create an enum DAYS to contain all days of a week and use that in your program.

I've cleaned up your code and it looks like this now:

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

enum DAYS
{
    SUNDAY,
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY
};

class DayOfTheWeek
{
public:
	void setDay(DAYS sday) { day = sday; }
	void printDay() const { cout << day; }
	DAYS getDay() { return day; }

private:
    DAYS day;
};

int main()
{
	DayOfTheWeek firstDay;

	int day = 0;
    firstDay.setDay(SUNDAY);

    std::string days[] = {"SUNDAY", "MONDAY", "TUESDAY", "WEDNESDAY",
                          "THURSDAY", "FRIDAY", "SATURDAY" };
    
	cout << "Welcome to the Set Day Program" << endl;
	cout << endl;
	cout << "please input what day it is:" << endl;
	cout << "1 = Sun" << endl;
	cout << "2 = Mon" << endl;
	cout << "3 = Tues" << endl;
	cout << "4 = Wed" << endl;
	cout << "5 = Thurs" << endl;
	cout << "6 = Fri" << endl;
	cout << "7 = Sat" << endl;
	cout << "Make your selection here: ";
	cin >> day;
        cout << days[day - 1] << endl;
	cout << endl;

	cout << "Today is " << days[firstDay.getDay()] << endl;

	return 0;
}

[Light02]

ok that did help at that part firstDay needs to be what the user inputted into the command line. also I'm assuming to do the second day I just need to do day = days[day+1];?

[JITHU]

Light02, on 11 July 2010 - 11:38 PM, said:

ok that did help at that part firstDay needs to be what the user inputted into the command line. also I'm assuming to do the second day I just need to do day = days[day+1];?

No, not really. You've to use day to get the next day, because arrays have a zero based indexing system. Also if the user inputs 7 as day, the next valid day is 1(Sunday)

std::string nextDay = days[(day == 7) ? 1 : day];

Once you got the user input, you should also check if the user's input is valid (1 <= day <= 7).

[NickDMax]

You know I see a lot of conditional logic that just does not need to be there...

Internally to the class day has a value of 0 though 6, to get the user "day" we add 1, to get convert the user's "day" into an internal one you just subtract 1.

Great so lets call "day" the one internal to the class (0-6) and "user_day" the user's version (1-7)

to find the next day:

next user_day = ((day + 1) % 7) + 1
N days in the future: user_day = ((day + N) % 7) + 1

here is one version of a program that does not use a class to solve the problem (which is probably what your assignment requires) but shows how an enum can be used to represent days of the week by overloading a couple operators:

#include <iostream>
#include <limits>

using namespace std;

//An enumeration for days... this counts as a "type"
enum DAYS {
    DAYS_BEGIN,
    SUNDAY = DAYS_BEGIN,
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY,
    DAYS_COUNT,
};

//Used for converting DAYS into a name when outputing
const char* DAY_NAMES[]= {
    "Sunday",
    "Monday",
    "Tuesday",
    "Wendesday",
    "Thursday",
    "Friday",
    "Saturday"
};

//Overload the operator  DAYS + int to return a proper day.
DAYS inline operator+(const DAYS& day, const int& v) {
    // note that the % operator might return a negative value if v < 0,
    // so we will correct for that by adding DAYS_COUNT
    int value = (static_cast<int>(day) + v) % DAYS_COUNT;
    return static_cast<DAYS>((value + DAYS_COUNT) % DAYS_COUNT);
}

//Overload the operator  DAYS + int to return a proper day.
DAYS inline operator-(const DAYS& day, const int& v) {
    return day + (-v);
}

//Overload the output operator so that cout << SUNDAY prints "Sunday"
std::ostream& operator<<(std::ostream& out, const DAYS& day) {
    //note the +0 ensures that we get a proper day (not DAYS_COUNT or -1 or something like that).
    return out << DAY_NAMES[day + 0];
}

// Convert a user input day (1-7) into a DAYS value.
// note that SATURDAY + 1 = SUNDAY, so this will use the operator+ above to do our conversion for us.
DAYS inline convertUserDay(int user_day) { return SATURDAY + user_day; }

//Get user input of a day
DAYS getUserDay();

int main() {
    DAYS day = getUserDay();
    cout << endl;
    cout << "Day: " << day << endl;
    cout << "Next Day: " << (day + 1) << endl;
    cout << "Day + 10: " << (day + 10) << endl;
    cout << "Day + 30: " << (day + 30) << endl;
    cout << "Day before: " << (day - 1) << endl;
    cout << "10 Days before: " << (day - 10) << endl;
    cout << "30 Days before: " << (day - 30) << endl;
    return 0;
};

DAYS getUserDay() {
    int user_day = -1;
    while (user_day < 0) {
        for(int i = 1; i <= DAYS_COUNT; i++) {
            // The convertUserDay function will conver from our expected input (1-7) to a DAYS type
            //    which is overloaded on ostream<< to print a day of the week...
            cout << i << ": " << convertUserDay(i) << '\n';
        }
        cout << "Please select 1-7: ";
        cin >> user_day;
        if(cin.bad() || user_day < 1 || user_day > 7) {
            cout << "\nERROR getting input, please enter a number 1-7\n" << endl;
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
            user_day = -1;
        }
    }
    return convertUserDay(user_day);
}