Not all code paths return a value when comparing 2 dates?

Question

I've been messing around with this for a long time and I couldn't find out what code path doesn't return a value. I'm trying to check if an entered date is later than the current date. I'd thank you if you can help me out with this problem. (Date is a class and the brackets are me testing it out with an example.)

public bool IsLater(Date d)
{                              //Date d = 2020/4/25  Date = 2020/4/21
    if (d.year > year) //false
    {
        return true;
    }
    if (d.year < year) //false
    {
        return false;
    }
    if (d.year == year)//true
    {
        if (d.month > month)//false
        {
            return true;
        }
        if (d.month < month)//false
        {
            return false;
        }
        if (d.month == month)//true
        {
            if (d.day > day)//true
            {
                return true;//ok
            }
            if (d.day < day)
            {
                return false;
            }
            else if (d.day == day)
                return false;
        }
    }
}

What datatypes are your year, month and day fields/properties? If they are nullable, then the paths do not hit. A solution is to remove the check for equal year and month, since before that, you check for less-than and greater-than. So those is-equal-to if's are redundant. — Maarten
– Maarten, Commented Apr 10, 2020 at 7:43
@Maarten right, my bad, i'm just a beginner so I make some rookie mistakes :) — FogelF7
– FogelF7, Commented Apr 10, 2020 at 7:53

Maarten · Accepted Answer · 2020-04-10 07:45:56Z

2

Personally, I would rewrite it to this. IMHO easier to read, and no 'not all paths ...' warning.

return
    d.year > year ||
    (d.year == year && d.month > month) ||
    (d.year == year && d.month == month && d.day > day)
    ;

answered Apr 10, 2020 at 7:45

Maarten

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1 Comment

FogelF7 Over a year ago

Thanks, can you explain in a couple words what every step does? appreciate your time

Just Shadow · Accepted Answer · 2020-04-10 07:53:10Z

1

I would use the DateTime class instead:

public bool IsLater(Date d)
{   
    DateTime a = new DateTimte (year, month, day);
    DateTime b = new DateTimte (d.year, d.month, d.day);
    return b > a;
}

answered Apr 10, 2020 at 7:53

Just Shadow

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Comments

Dmitrii Bychenko · Accepted Answer · 2020-04-10 12:43:38Z

First, you can let .Net make the work for you: why reinvent the wheel? Comparing dates is just > operator:

// Later: d is more than (year, month, day)
public bool IsLater(DateTime d) => d.Date > new DateTime(year, month, day);

If you insist on keeping your current routine, let compiler know that ifs are combined: turn if into else if and final if in each group into else

public bool IsLater(Date d)
{                              
    if (d.year > year) 
        return true;
    else if (d.year < year) 
        return false;
    else // we have nothing else but equal years
    {
        if (d.month > month)
            return true;
        else if (d.month < month)
            return false;
        else // nothing else but equal months
        {
            if (d.day > day)
                return true;
            else if (d.day < day)
                return false;
            else 
                return false;
        }
    }
}

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