CODEWITHSUNDEEP
javamethods
Tim
Tim

Reputation: 13

Developing week of month method

Basically in the following method I'm trying to say: If z2 does not equal 0, z2 - 1. else add 6 to z2. I know it's probably stupid but I'm quite new to programming. The code as follows:

int z2 = someValue;

    if(z2 != 0){
        z2--;
        }
    else{
         z2 + 6;
        }

Thanks

Upvotes: 1

Views: 45

Answers (2)

Joop Eggen
Joop Eggen

Reputation: 109597

The math operation for that is modulo, in java the operator %, remainder of division.

|   x | x % 3 |
|-----|-------|
|   6 |   0   |
|   5 |   2   |
|   4 |   1   |
|   3 |   0   |
|   2 |   2   |
|   1 |   1   |
|   0 |   0   |
|  -1 |  -1   |
|  -2 |  -2   |
|  -3 |   0   |
|  -4 |  -1   |

Using integer division / (5/3 == 1):

y % x == y - x * (y / x)

Notice the sign when one of the sides is negative.

In your case a decrement becomes:

z2 = (z2 - 1 + 7) % 7;

or short

z2 = (z2 + 6) % 7;

Care has been taken that the left hand side of % remains positive. The result then is in 0 .. 6.

For those interested in latin modulus is actually called the operation (a noun), but in an expression gets the adverbal ending o (ablativus): "34 modulo 7 is 6". But modulo will do fine used as noun.

Upvotes: 0

Tim Biegeleisen
Tim Biegeleisen

Reputation: 521997

You need to assign z2 to a value in the else condition:

if (z2 != 0) {
    z2--;         // same as z2 = z2 - 1
}
else {
    z2 += 6;      // same as z2 = z2 + 6
}

But we could do this with a single line of code, using a ternary expression:

z2 = z2 != 0 ? z2 - 1 : z2 + 6;

Upvotes: 1

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