Today I learned - Share your newly found knowledge!

Today I learned - Share your newly found knowledge! - Printable Version

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Re: Today I learned - Share your newly found knowledge! - Eoussama - 23.01.2018

Quote:

Originally Posted by GaByM

TIL this:
This isn't quite good because sizeof() doesn't work on this strings but it is still interesting.

sizeof() counts characters and stops when it reaches the null terminator (0, '\0', EOS)

Re: Today I learned - Share your newly found knowledge! - GaByM - 23.01.2018

Quote:

Originally Posted by Eoussama

sizeof() counts characters and stops when it reaches the null terminator (0, '\0', EOS)

No, strlen returns the amount of characters inside a string and stops at '\0'. sizeof() returns the size of the array, so

Код:

str[128] = "Hello"; printf("%i", sizeof(str)); //will print 128

Re: Today I learned - Share your newly found knowledge! - Spmn - 23.01.2018

You should never append to (or even edit) string literals. You will go out of bounds and most likely rewrite other literals.

Re: Today I learned - Share your newly found knowledge! - Dayrion - 23.01.2018

Quote:

Originally Posted by GaByM

TIL this:

You now can use strcat with a constant string (idk if i'm correct for this name) passed as parameter.

A better example:

This isn't quite good because sizeof() doesn't work on this strings but it is still interesting.

It can be easily bypassed.

PHP код:



FunctionGetActorTextLabel(text[], length = sizeof(text))

{

    strcat("YEA ->", text, length);

    print(text);

}

Re: Today I learned - Share your newly found knowledge! - Freaksken - 06.02.2018

TIL you can ignore parameters passed by reference (out parameters) by using a default value, just like you can with parameters passed by value (in parameters):

Код:

stock Float:DoSomething(playerid, &Float:a = 4.0) {
	a = 5.0;
	return 9.0;
}

The default value can be anything, since it will be ignored anyway.

Use:

Код:

DoSomething(0); //Returns 9.0

new Float:a;
DoSomething(0, a); //Returns 9.0 and variable 'a' contains 5.0

Re: Today I learned - Share your newly found knowledge! - ISmokezU - 06.02.2018

Quote:

Originally Posted by Freaksken

TIL you can ignore parameters passed by reference (out parameters) by using a default value, just like you can with parameters passed by value (in parameters):

Код:

stock Float:DoSomething(playerid, &Float:a = 4.0) {
	a = 5.0;
	return 9.0;
}

The default value can be anything, since it will be ignored anyway.

Use:

Код:

DoSomething(0); //Returns 9.0

new Float:a;
DoSomething(0, a); //Returns 9.0 and variable 'a' contains 5.0

Great find!

Would expect a tag mismatch with this, but this is great.

Re: Today I learned - Share your newly found knowledge! - PepsiCola23 - 12.02.2018

today i learned that there is not necessary to use

PHP код:



stock

in your gamemode.

for example,instead of

PHP код:



stock GetTruckNeedTracks(playerid)
{
    new truckneedtracks;
    new truckskill = GetPlayerTruckSkill(playerid);
    if(truckskill == 1) truckneedtracks = 35;
    else if(truckskill == 2) truckneedtracks = 100;
    else if(truckskill == 3) truckneedtracks = 220;
    else if(truckskill == 4) truckneedtracks = 450;
    return truckneedtracks;
}

you can simply write

PHP код:



GetTruckNeedTracks(playerid)
{
    new truckneedtracks;
    new truckskill = GetPlayerTruckSkill(playerid);
    if(truckskill == 1) truckneedtracks = 35;
    else if(truckskill == 2) truckneedtracks = 100;
    else if(truckskill == 3) truckneedtracks = 220;
    else if(truckskill == 4) truckneedtracks = 450;
    return truckneedtracks;
}

Re: Today I learned - Share your newly found knowledge! - Dayrion - 12.02.2018

Quote:

Originally Posted by PepsiCola23

...
you can simply write

PHP код:



GetTruckNeedTracks(playerid)

{

    new truckneedtracks;

    new truckskill = GetPlayerTruckSkill(playerid);

    if(truckskill == 1) truckneedtracks = 35;

    else if(truckskill == 2) truckneedtracks = 100;

    else if(truckskill == 3) truckneedtracks = 220;

    else if(truckskill == 4) truckneedtracks = 450;

    return truckneedtracks;

}

There is quick tutorial to explain when you can use the keyword stock: http://forum.sa-mp.com/showpost.php?...16&postcount=1
Now, you can learn something new. It's called "switch case" statement (« tutorial here!).

PHP код:



GetTruckNeedTracks(playerid)

{

    new truckneedtracks;

    new truckskill = GetPlayerTruckSkill(playerid);

    if(truckskill == 1) truckneedtracks = 35;

    else if(truckskill == 2) truckneedtracks = 100;

    else if(truckskill == 3) truckneedtracks = 220;

    else if(truckskill == 4) truckneedtracks = 450;

    return truckneedtracks;

}

Become (with some tiny optimisations)

PHP код:



GetTruckNeedTracks(playerid)

{

    switch(GetPlayerTruckSkill(playerid))

    {

        case 1: return 35;

        case 2: return 100;

        case 3: return 220;

        case 4: return 450; 

    }

    return 0;

}

Re: Today I learned - Share your newly found knowledge! - PepsiCola23 - 12.02.2018

Quote:

Originally Posted by Dayrion

PHP код:



GetTruckNeedTracks(playerid)

{

    new truckneedtracks;

    new truckskill = GetPlayerTruckSkill(playerid);

    if(truckskill == 1) truckneedtracks = 35;

    else if(truckskill == 2) truckneedtracks = 100;

    else if(truckskill == 3) truckneedtracks = 220;

    else if(truckskill == 4) truckneedtracks = 450;

    return truckneedtracks;

}

Become (with some tiny optimisations)

PHP код:



GetTruckNeedTracks(playerid)

{

    switch(GetPlayerTruckSkill(playerid))

    {

        case 1: return 35;

        case 2: return 100;

        case 3: return 220;

        case 4: return 450; 

    }

    return 0;

}

Thanks you,i ll try using this method

Re: Today I learned - Share your newly found knowledge! - Eoussama - 12.02.2018

Today I learned about a simple BATCH instruction that serves as a cool hack when testing/debugging.

1- First, open any text editor, and paste the following instructions

PHP код:



@echo off


:s

samp-server.exe

goto s

2- Save the file as “something.bat”
3- Run the .bat file

Now, whenever you change your code source and compile, no need to exit and re-execute your samp-server.exe, just type the exit command in the console, and it will automatically close and re-open it for you.

Re: Today I learned - Share your newly found knowledge! - rfr - 18.02.2018

Quote:

Originally Posted by Eoussama

Today I learned about a simple BATCH instruction that serves as a cool hack when testing/debugging.

1- First, open any text editor, and paste the following instructions

PHP код:



@echo off


:s

samp-server.exe

goto s

can't you write gmx on the console?

Re: Today I learned - Share your newly found knowledge! - Gforcez - 19.02.2018

Quote:

Originally Posted by rfr

can't you write gmx on the console?

That restarts the gamemode, not the entire server.

Re: Today I learned - Share your newly found knowledge! - Mobtiesgangsa - 02.03.2018

today i learned.... what means strtok

basicly strtok means

str - is a string == 1
tok - is a token == 2

strtok(const string[], &index)

1. its porpuse is to fetch textual declaration like the callback know as 'OnPlayerCommandText' with the parameters (playerid, cmdtext[])

2. tokes porpuse is to check indexe's or the given parameter of 'playerid'

here on the given example will show you how its done

example code:

Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
        new cmd[256+1], index;

        cmd = strtok(cmdtext, index);

        if(strcmp(cmd, "/info", true : false, 5)) < bool either its true or false
        {
                return true, false; < either it returns true or false
        }
        return false;
}

Re: Today I learned - Share your newly found knowledge! - GaByM - 06.03.2018

TIL that you can split a macro on multiple lines with '\'

PHP код:



#define add(%0,%1) ((%0)+(%1))


main()

{

    printf("%i",

        

        add(\

            5\

            ,\

            6\

            )


        );

}

Re: Today I learned - Share your newly found knowledge! - Eoussama - 06.03.2018

Quote:

Originally Posted by GaByM

TIL that you can split a macro on multiple lines with '\'

PHP код:



#define add(%0,%1) ((%0)+(%1))


main()

{

    printf("%i",

        

        add(\

            5\

            ,\

            6\

            )


        );

}

not only macros but literally anything, as far as I know, correct me if I'm wrong!

Re: Today I learned - Share your newly found knowledge! - Freaksken - 01.04.2018

TIL you can specify a variable width or precision by using an asterisk.

Код:

Width:
printf("%5d", 10);			//prints '   10'
printf("%*d", 5, 10);			//prints '   10'

printf("%5f", 3.1415926535);		//prints '    3.141592'
printf("%*f", 5, 3.1415926535);		//prints '    3.141592'

Precision:
printf("%.5f", 3.1415926535);		//prints '3.14159'
printf("%.*f", 5, 3.1415926535);	//prints '3.14159'

printf("%.5s", "abcdefghi");		//prints 'abcde'
printf("%.*s", 5, "abcdefghi");		//prints 'abcde'

This is useful in situations where you don't want to hardcode those values.

Re: Today I learned - Share your newly found knowledge! - Y_Less - 02.04.2018

YIL the internal buffer for formatting floating point numbers is 64 characters:

PHP код:



    new str[256];

    format(str, sizeof (str), "%7.0100f", 4.4);

    print(str);

    printf("%7.0100f", 4.4);

Should give numbers with 100 decimal places (mostly all zeros), but doesn't:

Код:

      4.40000009536743164062500000000000000000000000000000000000
      4.40000009536743164062500000000000000000000000000000000000

Edit:

I'll also expand on what Freaksken said (I didn't learn this today, I wrote the original code for it). You can combine variable width and precision, plus zero prefixes:

PHP код:



printf("%0*.*f", 3, 5, 4.4); // Gives "004.40000"

Even better, this can totally replace "substring" code:

PHP код:



new str[] = "How are you?"

printf("%.3s", str[4]); // Gives "are"

Re: Today I learned - Share your newly found knowledge! - kurta999 - 02.04.2018

Quote:

Originally Posted by Y_Less

YIL the internal buffer for formatting floating point numbers is 64 characters:

PHP код:



    new str[256];

    format(str, sizeof (str), "%7.0100f", 4.4);

    print(str);

    printf("%7.0100f", 4.4);

Should give numbers with 100 decimal places (mostly all zeros), but doesn't:

Код:

      4.40000009536743164062500000000000000000000000000000000000
      4.40000009536743164062500000000000000000000000000000000000

Edit:

I'll also expand on what Freaksken said (I didn't learn this today, I wrote the original code for it). You can combine variable width and precision, plus zero prefixes:

PHP код:



printf("%0*.*f", 3, 5, 4.4); // Gives "004.40000"

Even better, this can totally replace "substring" code:

PHP код:



new str[] = "How are you?"

printf("%.3s", str[4]); // Gives "are"

The latest example does work with sprintf in C?

Re: Today I learned - Share your newly found knowledge! - Y_Less - 02.04.2018

I have no idea sorry. As I said, the "*" functionality is something I added to SA:MP's format when I was a dev. Test it and make your own TIL post!

Re: Today I learned - Share your newly found knowledge! - coool - 22.06.2018

Today I learnt that:

PHP код:



new array[][] = {12,13};
printf("%i", array);

will output 8.