Tips & Tricks - Printable Version

Tips & Tricks - Printable Version

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Re: Tips & Tricks - LarzI - 07.03.2013

I recently realized that bit-flags are actually used in SA-MP itself: Player keys.

There are 19 keys defined in a_samp.inc, and they are set to powers of 2 (1, 2, 4, 8, 16, 32, 64).

If you put this simple code within OnPlayerKeyStateChange:

pawn Code:

printf( "%019b", newkeys );

Then you\'ll notice how this looks exactly like the use of bit-flags in this topic. For those who don\'t know, this is also why you should always check keys with & instead of ==.

@Slice: Is this where you got the inspiration for bit-flags?

Re: Tips & Tricks - MP2 - 07.03.2013

Quote:

Originally Posted by LarzI

If you put this simple code within OnPlayerKeyStateChange:

pawn Code:

printf( "%019b", newkeys );

Then you\'ll notice how this looks exactly like the use of bit-flags in this topic.

Interesting.

Re: Tips & Tricks - Stylock - 07.03.2013

Quote:

Originally Posted by LarzI

For those who don\'t know, this is also why you should always check keys with & instead of ==.

There\'s a tiny problem that you might come across. Example:

pawn Code:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if (newkeys & KEY_FIRE) // 4
    {
        print("MSG 1");
    }
    if (newkeys & KEY_JUMP) // 32
    {
        print("MSG 2");
    }
    return 1;
}

If you press KEY_FIRE, it will print:

pawn Code:

MSG 1
/*
 * newkeys = 000100
 */

If you press KEY_JUMP while holding KEY_FIRE, it will print:

pawn Code:

MSG 1
MSG 2
/*
 * newkeys = 100100
 */

If you release KEY_JUMP while holding KEY_FIRE, it will print:

pawn Code:

MSG 1
/*
 * newkeys = 000100
 */

That\'s why there\'s a third parameter, which you can use to detect when a key is pressed and released (not if a key is being held down).

Re: Tips & Tricks - Slice - 04.04.2013

All numbers in the assembler output are in hex, without leading zeroes and prefixes.

Re: Tips & Tricks - xeeZ - 04.04.2013

Quote:

Originally Posted by Y_Less

...

Isn't this the same as using -d0 (it removes breaks too)?

Re: Tips & Tricks - LarzI - 04.04.2013

Quote:

Originally Posted by Slice

All numbers in the assembler output are in hex, without leading zeroes and prefixes.

Yeah that's what I thought. I only asked because I assumed he switched out the code, rather than running them after eachother, which caused confusion (Due to A being 10 in base10)

Re: Tips & Tricks - newbienoob - 15.08.2013

Can I use ternary operator, bit-flags and multiple actions in one statement together? I mean like;

pawn Код:

//normal if-else statement
if(a == 0)
    a = 1;
    SetPlayerHealth(playerid, 100);
else
    a = 0;
    SetPlayerHealth(playerid, 0);

//ternary operator with multiple actions
a = (a == 0) ? 1, SetPlayerHealth(playerid, 100), print("Health: 100") : 0, SetPlayerHealth(playerid, 0), print("Health: 0"); 
//not sure here. correct me if I'm wrong  

//and how can I use bit flags with ternary operator? 
enum test: (<< = 1)
{
    a, // question here; what happen if i dont put = 1? like a = 1,
    b
}
new test:player[MAX_PLAYERS];
//so i want to toggle a to 0 or 1 using ternary operator. how can i do that?

Re: Tips & Tricks - sKgaL - 15.08.2013

Very useful, learned from this alot !

Re: Tips & Tricks - Slice - 15.08.2013

Quote:

Originally Posted by newbienoob

Can I use ternary operator, bit-flags and multiple actions in one statement together? I mean like;

pawn Код:

//normal if-else statement
if(a == 0)
    a = 1;
    SetPlayerHealth(playerid, 100);
else
    a = 0;
    SetPlayerHealth(playerid, 0);

//ternary operator with multiple actions
a = (a == 0) ? 1, SetPlayerHealth(playerid, 100), print("Health: 100") : 0, SetPlayerHealth(playerid, 0), print("Health: 0"); 
//not sure here. correct me if I'm wrong  

//and how can I use bit flags with ternary operator? 
enum test: (<< = 1)
{
    a, // question here; what happen if i dont put = 1? like a = 1,
    b
}
new test:player[MAX_PLAYERS];
//so i want to toggle a to 0 or 1 using ternary operator. how can i do that?

All of these questions you can answer yourself by testing it out, fyi.

pawn Код:

a = (a == 0) ? 1, SetPlayerHealth(playerid, 100), print("Health: 100") : 0, SetPlayerHealth(playerid, 0), print("Health: 0");

That might work, but even if it does it's horribly confusing!

pawn Код:

enum test: (<< = 1)
{
    a, // question here; what happen if i dont put = 1? like a = 1,
    b
}

All of them will have value 0 because 0 << 1 is still 0.

pawn Код:

new test:player[MAX_PLAYERS];
//so i want to toggle a to 0 or 1 using ternary operator. how can i do that?

Not sure what you mean. Start off from the examples in the main post and work your way from there. You'll figure it out.

If you need a place to quickly test things, use this: http://slice-vps.nl:7070/

Re: Tips & Tricks - newbienoob - 15.08.2013

Quote:

Originally Posted by Slice

All of these questions you can answer yourself by testing it out, fyi.

pawn Код:

a = (a == 0) ? 1, SetPlayerHealth(playerid, 100), print("Health: 100") : 0, SetPlayerHealth(playerid, 0), print("Health: 0");

That might work, but even if it does it's horribly confusing!

I tested with the link you gave me(I don't have pawno) but it gives me errors.

Код:

input(6) : error 1: expected token: ":", but found ","
input(6) : error 1: expected token: ";", but found ":"
input(6) : error 29: invalid expression, assumed zero
input(6) : fatal error 107: too many error messages on one line

The codes

pawn Код:

main()
{
    new a;
    a = (a == 0) ? 1, print("1") : 0, print("0");
}

Quote:

Originally Posted by Slice

pawn Код:

enum test: (<< = 1)
{
    a, // question here; what happen if i dont put = 1? like a = 1,
    b
}

All of them will have value 0 because 0 << 1 is still 0.

hmm I thought we should set it all to 0?

Quote:

Originally Posted by Slice

pawn Код:

new test:player[MAX_PLAYERS];
//so i want to toggle a to 0 or 1 using ternary operator. how can i do that?

Not sure what you mean...

I mean like;

pawn Код:

enum ASD : (<< = 1)
{
    One = 1,
    Two,
    Three
}
new ASD:DSA[MAX_PLAYERS];

//So how can I use ternary operator here to set Two to 0 or 1?

Re: Tips & Tricks - Slice - 15.08.2013

Explain what it is you want to do instead, and I'll show you the best way to do that.

Re: Tips & Tricks - newbienoob - 15.08.2013

Ok, lets say that I want to make /duty command(admin duty on/off).

pawn Код:

//in normal way

new bool:Duty[MAX_PLAYERS];

CMD:duty(playerid)
{
    if(Duty[playerid] == false)
    {
        SendClientMessage(playerid, -1, "You are now on duty.");
        Duty[playerid] = true;
    }
    else
    {
        SendClientMessage(playerid, -1, "You are now off duty.");
        Duty[playerid] = false;
    }
    return 1;
}

//So can I use bit-flags and ternary operator together to create that command?

EDIT: here's another example

pawn Код:

enum DutyFlag:(<< = 1)
{
    Duty = 1
}
new DutyFlag:g_Duty[MAX_PLAYERS];

//OnPlayerConnect
g_Duty[playerid] = DutyFlag:0;


//Ok so, the main question is, can I change if-else statement in the command below to ternary operator?
CMD:duty(playerid)
{
    if(g_Duty[playerid] & Duty) *
    {
        g_Duty[playerid] |= Duty; 
        SendClientMessage(playerid, -1, "Now on duty!");
    }
    else
    {
        g_Duty[playerid] &= Duty;
        SendClientMessage(playerid, -1, "Now off duty!");
    }
    return 1;
}

* I'm not sure here, is it 0?

Re: Tips & Tricks - Slice - 15.08.2013

You can, but it's not worth it.

pawn Код:

g_Duty[playerid] = CONDITION ? (g_Duty[playerid] | Duty) : (g_Duty[playerid] & ~Duty);

Re: Tips & Tricks - newbienoob - 15.08.2013

Got it! Thanks. What about this?

Quote:

Originally Posted by Slice

pawn Code:

a = (a == 0) ? 1, SetPlayerHealth(playerid, 100), print("Health: 100") : 0, SetPlayerHealth(playerid, 0), print("Health: 0");

That might work, but even if it does it's horribly confusing!

I tested with the link you gave me(I don't have pawno) but it gives me errors.

Code:

input(6) : error 1: expected token: ":", but found ","
input(6) : error 1: expected token: ";", but found ":"
input(6) : error 29: invalid expression, assumed zero
input(6) : fatal error 107: too many error messages on one line

The codes

pawn Code:

main()
{
    new a;
    a = (a == 0) ? 1, print("1") : 0, print("0");
}

Can I use multiple actions in ternary operator?

Re: Tips & Tricks - Y_Less - 15.08.2013

You can, but not like that, and why would you? That's what structured "if"s are for - ternarys shouldn't really be used unless there's no alternative.

Re: Tips & Tricks - newbienoob - 15.08.2013

1 line instead of many which makes my script looks simple and clean.
Btw, what am I doing wrong? Can you show me how?

Re: Tips & Tricks - Y_Less - 15.08.2013

Trust me, it doesn't look either simple OR clean! One long line doing lots of different things is much more complicated than lots of lines each doing one thing.

Re: Tips & Tricks - newbienoob - 15.08.2013

Ok, thank you for answering my questions.
Just one more question about "char-arrays".
Does it only for booleans? Can I put 'char' on every arrays? Like this;

pawn Code:

new 
    bool:Duty[MAX_PLAYERS char],
    bool:Duty1[MAX_PLAYERS char],
    String[128 char],
    String1[128 char],
    Pickups[30 char],
    Pickups1[30 char];

Sorry if I'm asking so many questions. I'm learning

Re: Tips & Tricks - Y_Less - 15.08.2013

You can put "char" on any array where the highest value to be stored will be 255, and the lowest 0 (or -128 - 127).

Re: Tips & Tricks - dipsnark - 19.12.2013

Did you test bit-flags? BitFlag_Get macro awlays returns zero.