model hud

so i made this model hud, it's pretty basic, not something i plan on selling, just for personal use. all works well except one thing, when pressing the "back" button, it doesn't loop back to the end when it gets to 0, instead it continues to count down. when it gets to the end when pressing the "next" button it loops around the beginning like it should. can someone spot my error? and other advice on the script is welcome, it's just something i threw together.

string current;
integer i = 0;
integer num;
floattext(string animname)
{
    integer pos = i + 1;
    string text = "Now Playing " + current + "\n" + (string)pos + " of " + (string)num;
    llSetText(text,<1.0,1.0,1.0>,1.0);
}
    
default
{
    attach(key id)
    {
        if(id)
        {
            llRequestPermissions(id,PERMISSION_TRIGGER_ANIMATION);
            state animate;
        }
    }
}

state animate
{
    state_entry()
    {
        num = llGetInventoryNumber(INVENTORY_ANIMATION);
        current = llGetInventoryName(INVENTORY_ANIMATION,i);
        llStartAnimation(current);
        floattext(current);
    }
    
    touch_start(integer n)
    {
        integer linknum = llDetectedLinkNumber(0);
        string name = llToLower(llGetLinkName(linknum));
        if(name == "pose")
        {
            llRezObject("Pose Ball",llGetPos() + <1.0,0.0,0.0>*llGetRot(),ZERO_VECTOR,ZERO_ROTATION,0);
        }
        else if(name != "pose")
        {
            if(name == "next"){i = (i + 1)%num;}
            else if(name == "back"){i = (i - 1)%num;}
            else if(name == "begin"){i = 0;}
            llStopAnimation(current);
            llOwnerSay((string)i);
            current = llGetInventoryName(INVENTORY_ANIMATION,i);
            floattext(current);
            llStartAnimation(current);
        }        
    }
    
    changed(integer change)
    {
        if(change & CHANGED_INVENTORY)
        {
            num = llGetInventoryNumber(INVENTORY_ANIMATION);
        }
    }
}

else if(name == "back"{if (--i < 0) i = num - 1;}

... or whatever variation floats your boat.

i got it, i changed this line

else if(name == "back"{i = (i - 1)%num;}

into

else if(name == "back"{i = (i - 1+num)%num;}

not sure why it works, but it does lol

i got it, i changed this line

else if(name == "back"{i = (i - 1)%num;}

into

else if(name == "back"{i = (i - 1+num)%num;}

not sure why it works, but it does lol

and obviously this line

llOwnerSay((string)i);

is only to see what index it's actually trying to use