Snippet GetRandomEven()

[dare2care]

Shows you how to get a random even integer.

function IsEven takes integer number returns boolean
    return ( number / 2 ) * 2 == number
endfunction

function GetRandomEven takes integer min, integer max returns integer
    if min == max and IsEven(min) then
        return min
    elseif max < min then
        return GetRandomInt((max + 1) / 2, (min + 1) / 2 ) * 2       
    elseif min != max then
        return GetRandomInt((min + 1) / 2, (max + 1) / 2 ) * 2
    endif
    return 0
endfunction

Examples

GetRandomEven(1, 1) //outputs 0
GetRandomEven(9, 10) // ouputs 10
GetRandomEven(6, 8) // outputs 6 or 8
GetRandomEven(8, 6) // ouputs 6 or 8

 

[DrEvil]

GetRandomInt(startNum/2,endNum/2) * 2

EDIT : Yes , your example is correct.
( My bad , didn't see )

EDIT2 : Arg , thought u said How not S'how's

This is not really a snippet... Anyone could do this.
But let's see what other people think...

 

[dare2care]

GetRandomInt(startNum/2,endNum/2) * 2

That's what I posted.

 

[SerraAvenger]

not fairly accurate.

function GetRandomEven takes integer min, integer max returns integer result
       return GetRandomInt((min+1) / 2, (max+1) / 2) * 2
endfunction


function GetRandomOdd takes integer min, integer max returns integer result
       return GetRandomInt((min) / 2, (max) / 2) * 2 + 1
endfunction

EDIT: Still not totally ok^^
You will have to take care when min = max and min being odd/even (depending on the function), in which case there should be no result at all; It will give out the next highest integer though.

 

[dare2care]

@

function GetRandomEven takes integer min, integer max returns integer result
       return GetRandomInt((min+1) / 2, (max+1) / 2) * 2
endfunction

call GetRandomEven(6, 10)

That gives me a random even int between 7 and 11? Why do you need that?

Is there any round function in JASS?

 

[SerraAvenger]

@

function GetRandomEven takes integer min, integer max returns integer result
       return GetRandomInt((min+1) / 2, (max+1) / 2) * 2
endfunction

call GetRandomEven(6, 10)

That gives me a random even int between 7 and 11? Why do you need that?

Is there any round function in JASS?

It always rounds down when you do integer division.

 

[Romek]

I fail to see how this is even remotely useful.
And in any case where it is useful, I doubt people would come to this site, and search out a "EvenRandomInteger" snippet.

 

[dare2care]

It always rounds down when you do integer division.

Any function to round up?

 

[SerraAvenger]

Any function to round up?

Add +(dividend/2) before dividing?

EDIT:

function GetRandomEven takes integer min, integer max returns integer // no result here!
       if (min != max) then // forgot a then!
             return GetRandomInt((min+1) / 2, (max+1) / 2) * 2
       endif
       return 0 // min is most probably odd, in which case returning min is a bad idea. 
endfunction

please learn JASS syntax before you post snippets^^

 

[Romek]

Add 0.99999 to the result.
Or add 0.5 to round correctly.

 

[dare2care]

Updated.

 

[SerraAvenger]

Add 0.99999 to the result.
Or add 0.5 to round correctly.

In an integer division?
lol. My dear romek, you totally missed the point^^

EDIT: Yeah. Now he made the syntax even worse. GJ, romek...
@dare2care: adding 0.5 will convert your beloved integer to a real. Your GetRandomInt() function, however, requires integers as arguments, not reals. Now you will even need two additional function calls (R2I()) which will make the code even harder to read and slower.

And even if you did, nothing had changed becouse your friggin integer division first rounds down, then you add 0.5, and round down again. You, too, did totally miss the point >_>

EDIT2:
Please fix the syntax before making it even worse. You still return integer "result" and have no then after your if.

 

[Romek]

This doesn't even compile.
"function GetRandomEven takes integer min, integer max returns integer result"
would syntax.

And what if min is odd? Then you have a problem.
I ask again, why would anyone want this?
It's quite useless. And complicated for something so useless.

return R2I(GetRandomReal(min, max)/2.)*2

> In an integer division?
One would assume you're converting.

 

[dare2care]

Fixed errors. It now compiles properly.

 

[Romek]

> Fixed errors. It now compiles properly.
No it doesn't.

 

[SerraAvenger]

This doesn't even compile.
"function GetRandomEven takes integer min, integer max returns integer result"
would syntax.

And what if min is odd? Then you have a problem.

Am I speaking french or why does noone read my posts >_>
I said the same in my last three posts^^

return R2I(GetRandomReal(min, max)/2.)*2

Another approach that does neither take into account the
GetRandomEven( 3, 3 ) nor the ( odd, odd )/( odd, even )/( even, odd ) problem

> In an integer division?
One would assume you're converting.

Just for rounding up^^?

 

[dare2care]

> Fixed errors. It now compiles properly.
No it doesn't.

It does with JassHelper.

>Another approach that does neither take into account the GetRandomEven( 3, 3 )

Already fixed that, look at original post.

 

[SerraAvenger]

integer result

should not compile.
should be

integer

instead

Nevertheless there is still an uneeded local variable == 2 unnecessary lines and 4 bytes of unneeded memory.
And it still doesn't work.
Just ffs copy and paste
a)

return R2I(GetRandomReal(min, max)/2. + 0.9)*2

or
b)

             return GetRandomInt((min+1) / 2, (max+1) / 2) * 2

>Another approach that does neither take into account the GetRandomEven( 3, 3 )

Already fixed that, look at original post.

I quoted romek's approach.

 

[Romek]

> It does with JassHelper.
That's a bug with Jasshelper then.

Anyway, this is graveyarded.
It's utterly useless, (should have) syntax errors, and is poorly coded (especially for something so simple).
I'm surprised this even managed to get as many replies as it has.

> GetRandomEven( 3, 3 ) nor the ( odd, odd )/( odd, even )/( even, odd ) problem
Well, what would you expect GetRandomEven(3, 3) to return? ._.

 

[SerraAvenger]

> GetRandomEven( 3, 3 ) nor the ( odd, odd )/( odd, even )/( even, odd ) problem
Well, what would you expect GetRandomEven(3, 3) to return? ._.

At least not 2 or 4 ^.-
Perhaps 0.