Ranges not usable with switch cases, need good alternative

Question

I'm trying to create a leveling system for a text based RPG that I'm making. The problem I'm running into is that it seems ranges won't work with switch cases. Here is what I have:

int exp = 0, level = 1, hp = 10, hpmax = 10;

if (exp >= 262144) exp = 262144;

switch (exp)            
{
case (4 - 15):
    level = 2;
    hp = 12;
    hpmax = 12;
    break;

case (16 - 63):
    level = 3;
    hp = 14;
    hpmax = 14;
    break;

case (64 - 255):
    level = 4;
    hp = 16;
    hpmax = 16;
    break;

case (256 - 1023):
    level = 5;
    hp = 18;
    hpmax = 18;
    break;

case (1024 - 4095):
    level = 6;
    hp = 20;
    hpmax = 20;
    break;

case (4096 - 16383):
    level = 7;
    hp = 20;
    hpmax = 20;
    break;

case (16384 - 65535):
    level = 8;
    hp = 22;
    hpmax = 22;
    break;

case (65536 - 262143):
    level = 9;
    hp = 24;
    hpmax = 24;
    break;

case (262144 - 999999999):
    level = 10;
    hp = 26;
    hpmax = 26;
    break;

Yes, I realize this doesn't do what I want it to do. I'm not quite satisfied with the alternatives that I've found. I'm looking for the simplest solution. I'm new to programming so any help would be appreciated.

Bernhard Barker · Accepted Answer · 2013-02-14 20:10:00Z

1

Note if hpmax is always = hp, you can set that at the end, you don't need to have it in all the cases.

Using if-else:

if (4 <= exp && exp <= 15)
{
  level = 2;
  hp = 12;
}
else if (16 <= exp && exp <= 63)
{
  level = 3;
  hp = 14;
}
else if ...

hpmax = hp; // set hpmax afterwards

Simplifying the above:

if (exp < 4) // 0-3
  ; // do nothing
else if (exp < 16) // 4-15
  ...
else if (exp < 64) // 16-63
  ...

Or simplifying with a function: (similar to utnapistim's suggestion)

bool in(int exp, int start, int end) { return start <= exp && exp <= end; };

if (in(exp, 4, 15)) // 4-15
  ...
else if (in(exp, 16, 63)) // 16-63
  ...

Using log-base-2:

switch((int)(Math.Log(exp)/Math.Log(2)))
{
  case 2: case 3: // 4-15
    level = 2;
    hp = 12;
    break;
  case 4: case 5: // 16-63
    ...
  default: // 262144-999999999
    ...
}
hpmax = hp;

A mathematical (way shorter) solution: (doesn't work for all cases, just something to derive a solution from)

int log = (int)(Math.Log(exp)/Math.Log(2));
level = 1+log/2;
hp = hpmax = 10+level*2;

edited Feb 14, 2013 at 20:10

answered Feb 14, 2013 at 13:59

Bernhard Barker

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2 Comments

Jared Price Over a year ago

Your first suggestion doesn't seem to be working, unless I'm doing something wrong. I'm using C# by the way. I wrote a method to increase my HP for testing. When I type "iddqd" it increases my exp. I also wrote a method for a stats command to show my characters stats. Here is what I'm seeing in my program: stats Frank =================== Level:1 Experience:0 Hit Points:10/10 iddqd stats Frank =================== Level:1 Experience:4 Hit Points:10/10 iddqd stats Frank =================== Level:1 Experience:20 Hit Points:10/10

Bernhard Barker Over a year ago

@JaredPrice Edited. All the supplied ways of doing things should work. If you're having trouble, you could paste your code to pastebin.com or somewhere similar and I can have a look.

utnapistim · Accepted Answer · 2013-02-14 13:58:19Z

Conceptually, you could use a function for checking.

Example using c++:

inline bool in_range(int min, int max, int value)
{ return min <= value && value <= max; }

// ....

        int exp = 0, level = 1, hp = 10, hpmax = 10;

        if (exp >= 262144) exp = 262144;

        if (in_range(0, 15, exp)) {
            level = 2;
            hp = 12;
            hpmax = 12;
        } else if (in_range(16, 63, exp)) {
            level = 3;
            hp = 14;
            hpmax = 14;
        } else if ...

KevinM · Accepted Answer · 2013-02-14 14:00:42Z

You're probably looking for if-then-else statements:

           int exp = 0, level = 1, hp = 10, hpmax = 10;


            if ((4 >= exp) && (exp <= 15)){
                level = 2;
                hp = 12;
                hpmax = 12;
            } elseif ((16 >= exp) && (exp <= 63)){
                level = 3;
                hp = 14;
                hpmax = 14;
            } elseif ((64 >= exp) && (exp <= 255)){
                level = 4;
                hp = 16;
                hpmax = 16;
            } elseif ((256 >= exp) && (exp <= 1023)){
                level = 5;
                hp = 18;
                hpmax = 18;
            } elseif ((256 >= exp) && (exp <= 1023)){

             .... etc, you know what do paste here, etc ....

            } elseif ((262144 >= exp) && (exp <= 999999999)){
                level = 10;
                hp = 26;
                hpmax = 26;
            } else {
                ... you probably don't need anything here ...
                ... you already set defaults in the init up top...
            }

Frhay · Accepted Answer · 2013-02-14 14:02:44Z

I think you should use a combination of definition array and consecutive if to find the right level for the character, I'll show you a sample with random (and fewer) values...

<?php
// Definition of experience needed per level, and hp given
$levelsData = array( 1 => array( "exp" => 0,
                                 "hp" => 10),
                     2 => array( "exp" => 4,
                                 "hp" => 12),
                     3 => array( "exp" => 15,
                                 "hp" => 16),
                     4 => array( "exp" => 27,
                                 "hp" => 34),
                     5 => array( "exp" => 500,
                                 "hp" => 120));

// Finding user level, giving $exp as current exp
foreach ($levelsData as $level => $data) {
    if ($exp < $data['exp']) {
        break;
    }
}

// Setting data, we already have $level as the actual level+1
$level--;
$data = $levelsData[$level];
$hp = $data['hp'];
$maxHp = $hp;
?>

Not sure what language OP is working in, but it doesn't look like PHP to me.
Probably not, but being no language specified, I used the one I'm better at... the strategy is what counts here, I hope... :)

Jared Price · Accepted Answer · 2013-02-14 17:53:17Z

This is what I ended up using:

static void LevelSystem()

    {
        if ((4 <= exp) && (exp <= 15))
        {
            level = 2;
            hpmax = 12;
        }

        else if ((16 <= exp) && (exp <= 63))
        {
            level = 3;
            hpmax = 14;
        }

        else if ((64 <= exp) && (exp <= 255))
        {
            level = 4;
            hpmax = 16;
        }

        else if ((256 <= exp) && (exp <= 1023))
        {
            level = 5;
            hpmax = 18;
        }

        else if ((1024 <= exp) && (exp <= 4095))
        {
            level = 6;
            hpmax = 20;
        }

        else if ((4096 <= exp) && (exp <= 16383))
        {
            level = 7;
            hpmax = 20;
        }

        else if ((16384 <= exp) && (exp <= 65535))
        {
            level = 8;
            hpmax = 22;
        }

        else if ((65536 <= exp) && (exp <= 262143))
        {
            level = 9;
            hpmax = 24;
        }

        else if ((262144 <= exp) && (exp <= 999999998))
        {
            level = 10;
            hpmax = 26;
        }
        else if (exp >= 999999999)
        {
            exp = 999999999;
            level = 99;
            hp = 999999999;
            hpmax = 999999999;
        }
    }

I made that ridiculous number for testing purposes for later, but I put it all in a method so I can call it whenever I need to check exp. I tested this out and it works exactly how I want it to.

Thanks for the help everyone!

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