Adding multiple numbers in if and case statements

Question

I'm developing my first game app for the iphone, and I'm still a bit nooby in objective-c.

The game is coming along fine but i'm stuck on a little problem...

I want to make it so that for every 20 kills, you get +1 life, I know how to do that but with poorly written code such as this...:

    switch (kills) {

        case 20:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;

        case 40:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;

        case 60:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;
        case 80:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;
        case 100:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;

        case 120:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;
        case 140:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;
        case 160:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;

        case 180:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

            break;

        case 200:

            lives++;

            livescount.text = [NSString stringWithFormat:@"%i", lives];

and so on.... I don't want to keep writing this till infinity lol

I know for a fact that this is an improper way to write the code. Can anyone give me a proper code for every 20 kills = +1 life. I would probably spot on and understand how the code works too.

Arnaud · Accepted Answer · 2013-09-06 04:28:33Z

4

Use the modulo operator (%) that return the remaider of division by 20 ; also check that the number of kills is different from zero.

if (kills != 0 && kills % 20 == 0) {
    lives++;
    livescount.text = [NSString stringWithFormat:@"%i", lives];
}

edited Sep 6, 2013 at 4:28

answered Sep 6, 2013 at 4:16

Arnaud

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4 Comments

rmaddy Over a year ago

This gives an extra life if there are no kills.

user2748685 Over a year ago

Can someone further explain what it means? I want to make sure I know what it is so that I can understand Objective-C a bit more.

Arnaud Over a year ago

The % operator is the modulo operator - it returns the remainder of the division. For example, the quotient of the integer division of 23 by 10 is 2 : 23 / 10 = 2 ; the remainder of the integer division of 23 by 10 is 3 : 23 % 10 = 3. See wikipedia, paragraph "Division of integers"

Arnaud Over a year ago

In your case, as you need to run the code whenever kills = 20, 40, 60, 80... it is equivalent to check that the reminder of the division by 20 is zero.

Chris Nolet · Accepted Answer · 2013-09-06 07:24:52Z

0

You should use mod, so:

if (kills && kills % 20 == 0) {
  lives++;
}

Mod (%) returns the remainder of the division: so in this case if kills is exactly divisible by 20 it will return zero.

Good luck!

edited Sep 6, 2013 at 7:24

answered Sep 6, 2013 at 4:16

Chris Nolet

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11 Comments

rmaddy Over a year ago

This gives an extra life if there are no kills.

Suryakant Sharma Over a year ago

what about this if(kills != 0 && kills%20 == 0 )

user2748685 Over a year ago

This would probably work but i don't know i'm not on my mac at the moment... However I don't want my kills to be 0 again, it will mess up the score, I guess i'll make another invisible int such as kills2 but it would be so much work lol

rmaddy Over a year ago

@user2748685 This does not modify the value of kills.

user2748685 Over a year ago

@rmaddy hmmm then why does it have 20 == "0"?

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