Bit operation - Printable Version

Bit operation - Printable Version

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Bit operation - RakeDW - 15.09.2018

Hi, I need help with bit operations..
Lets say I have all bits "turned on"

Код:

11111111111111111111111111111111

Now I have variables ex.

Код:

new myVar = 8;

And I must turn off 8th bit and get something like

Код:

11111110111111111111111111111111

I tried

Код:

new data; // all bits off
new myVar1 = 2, myVar2 = 8, myVar3 = 12;
data |= myVar1; // turn on 2nd bit
data |= myVar1; // turn on 12th bit

print((data & myVar1) ? ("myVar1 passed") : ("myVar1 failed"));
print((data & myVar2) ? ("myVar2 passed") : ("myVar2 failed"));
print((data & myVar3) ? ("myVar3 passed") : ("myVar3 failed"));

// Out: 
[20:49:25] myVar1 passed
[20:49:25] myVar2 failed
[20:49:25] myVar3 failed

Re: Bit operation - RakeDW - 17.09.2018

bump

Re: Bit operation - Grim_ - 17.09.2018

Read through this https://sampforum.blast.hk/showthread.php?tid=177523

Re: Bit operation - Dayrion - 17.09.2018

Код:

11111110111111111111111111111111

This is not the 8th bit.

If you try to "turn off" a specify bit, you can't do it with the OR logical operation because 1 OR 0 = 1 everytime.
You need to use AND logical operator with NOT.

PHP код:



main()

{

    new test_value = 0b1111111111; // there is 10, 1


    test_value &= ~(1 << 7); // 8-1

    printf("%b", test_value);

}

Re: Bit operation - NaS - 17.09.2018

Quote:

Originally Posted by RakeDW

Hi, I need help with bit operations..
Lets say I have all bits "turned on"

Код:

11111111111111111111111111111111

Now I have variables ex.

Код:

new myVar = 8;

And I must turn off 8th bit and get something like

Код:

11111110111111111111111111111111

I tried

Код:

new data; // all bits off
new myVar1 = 2, myVar2 = 8, myVar3 = 12;
data |= myVar1; // turn on 2nd bit
data |= myVar1; // turn on 12th bit

print((data & myVar1) ? ("myVar1 passed") : ("myVar1 failed"));
print((data & myVar2) ? ("myVar2 passed") : ("myVar2 failed"));
print((data & myVar3) ? ("myVar3 passed") : ("myVar3 failed"));

// Out: 
[20:49:25] myVar1 passed
[20:49:25] myVar2 failed
[20:49:25] myVar3 failed

First off, 8 fails because you didn't set it.
Furthermore you use myVar1 twice and expect it to do different things (but in fact you set the 2nd twice).

Your test should be:

Код:

data |= myVar1; // turn on 2nd bit
data |= myVar2; // turn on 8th bit
data |= myVar3; // turn on 12th bit

But even that isn't correct as Dayrion said. Your test was just wrong additionally to the operations.

Also 8 wouldn't set the 8th bit. 8 in binary is not equal to b10000000. 8 is b1000.
12 is also two bits that get set. It's b1100

Re: Bit operation - RakeDW - 17.09.2018

Fixed it.

Код:

 
new some_var;
new bit_pos_to_turn_on = 15;
some_var |= (1 << bit_pos_to_turn_on);

printf((some_var & (1 << bit_pos_to_turn_on)) ? ("pass") : ("fail"));

anyway thanks to all