How to check whether date is valid

Question

I can use only parseInt and if-else-statements and I'm stuck right now. I understood the logic, but I can't control for example february dates and leap years. I wrote some statements about it.

boolean leap = false;
if (((year % 4) == 0) && ((year % 100) == 0)
        && ((year % 400) == 0) && ((year % 4000) != 0))
    leap = true;
else
    leap = false;

But I can't contact with february. Can you help me please?

Can you provide a more complete example of your code? for instance, where are you getting `year` from? — Brian Driscoll, Oct 14 '14 at 19:02
possible duplicate of http://stackoverflow.com/questions/1021324/java-code-for-calculating-leap-year — StackFlowed, Oct 14 '14 at 19:02
"leap" will equate to true only on multiples of 400 that are not multiples of 4000, which is not how to calculate for leap year :). — Matt Jones, Oct 14 '14 at 19:03
possible duplicate of [leap year calculation](http://stackoverflow.com/questions/725098/leap-year-calculation) — Brian Driscoll, Oct 14 '14 at 19:07
`return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;` — nachokk, Oct 14 '14 at 19:18
What puzzles me is what “But I can't contact with february” might want to tell me… — Holger, Oct 14 '14 at 19:43

score 1 · Accepted Answer · answered Oct 14 '14 at 19:07

1

Leap year can be evaluated by:

    if ((year % 4 == 0) && (year % 100 != 0))
    {
        leap = true;
    }
    else if (year % 400 == 0)
    {
        leap = true;
    }
    else
    {
        leap = false;
    }

answered Oct 14 '14 at 19:07

Matt Jones

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score 0 · Answer 2 · answered Oct 14 '14 at 19:18

0

I'd simplify @Matt Jones answer but that's just me.

leap = false;
if(((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0)){
    leap = true;
}

same thing basically but a little less typing :)

answered Oct 14 '14 at 19:18

erp

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If you want to reduce typing, why are you still repeating the useless `if` statement and all these annoying braces? Just `leap = year % 4 == 0 && year % 100 != 0 || year % 400 == 0;` is enough. – Holger Oct 14 '14 at 19:42

How to check whether date is valid

2 Answers2