unsigned right shift

[Lorentzos Roussos]

Hi , in javascript theres >>> and its called an "unsigned right shift"

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Unsigned_right_shift

Is >> the equivalent in mql5 ?

Thanks 

[Fernando Carreiro]

Yes ... Documentation on MQL5: Language Basics / Operations and Expressions / Bitwise Operations

Right Shift

The binary representation of x is shifted to the right by y digits. If the value to shift is of the unsigned type, the logical right shift is made, i.e. the freed left-side bits will be filled with zeroes.

If the value to shift is of a sign type, the arithmetic right shift is made, i.e. the freed left-side digits will be filled with the value of a sign bit (if the number is positive, the value of the sign bit is 0; if the number is negative, the value of the sign bit is 1).

x = x >> y;

Left Shift

The binary representation of x is shifted to the left by y digits, the freed right-side digits are filled with zeros.

x = x << y;

[Lorentzos Roussos]

Fernando Carreiro #:

Yes ... Documentation on MQL5: Language Basics / Operations and Expressions / Bitwise Operations

Right Shift

The binary representation of x is shifted to the right by y digits. If the value to shift is of the unsigned type, the logical right shift is made, i.e. the freed left-side bits will be filled with zeroes.

If the value to shift is of a sign type, the arithmetic right shift is made, i.e. the freed left-side digits will be filled with the value of a sign bit (if the number is positive, the value of the sign bit is 0; if the number is negative, the value of the sign bit is 1).

Left Shift

The binary representation of x is shifted to the left by y digits, the freed right-side digits are filled with zeros.

thanks.

I did not explain this properly ,sorry .I am forced to use an int or long as typescript has the type "number" (a long judging by the outcome in typescript/javascript)

also , off topic , shouldn't (-32)>>7 be zero ?

[Fernando Carreiro]

Lorentzos Roussos #: I did not explain this properly ,sorry .I am forced to use an int or long as typescript has the type "number" (a long judging by the outcome in typescript/javascript)

also , off topic , shouldn't (-32)>>7 be zero ?

It is best to shift unsigned integers, or else it will seem a little confusing.

-32 = 0xFFFFFFE0 (11111111 11111111 11111111 11100000)

shifting it 4 bits to right, makes it 268435454 = 0x0FFFFFFE (00001111 11111111 11111111 11111110)

shifting it 7 bits to right, makes it 33554431 = 0x01FFFFFF (00000001 11111111 11111111 11111111)

EDIT: I see what you mean. According to the documentation is should be filling in the left bit with the sign bit and not zero.

Show your code, as there might be a typecast into an unsigned which is causing the issue.

[Alain Verleyen]

Lorentzos Roussos:

Hi , in javascript theres >>> and its called an "unsigned right shift"

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Unsigned_right_shift

Is >> the equivalent in mql5 ?

Thanks 

There is no unsigned right shift in mql5. You need to be creative.

// Not compiled, not tested.

union toShift
{
    int  vsigned;
    uint vnotsigned;
};

void Start()
{
    toShift i;
    i.vsigned = -32;
    Print(i.vnotsigned>>7);
}

[Lorentzos Roussos]

Fernando Carreiro #:

It is best to shift unsigned integers, or else it will seem a little confusing.

-32 = 0xFFFFFFE0 (11111111 11111111 11111111 11100000)

shifting it 4 bits to right, makes it 268435454 = 0x0FFFFFFE (00001111 11111111 11111111 11111110)

shifting it 7 bits to right, makes it 33554431 = 0x01FFFFFF (00000001 11111111 11111111 11111111)

EDIT: I see what you mean. According to the documentation is should be filling in the left bit with the sign bit and not zero.

Show your code, as there might be a typecast into an unsigned which is causing the issue.

it does it for the unsigned types but not for the signed i think . Thanks

   int a=-32;
   for(int i=0;i<8;i++){
   int sh=a>>i;
   Print(IntegerToString(a)+" >> "+IntegerToString(i)+" = "+IntegerToString(sh));
   } 

[Lorentzos Roussos]

Alain Verleyen #:
id Start() {     toShift i;     i.vsigned = -32;     Print(i.vnotsigned>>7); }

thanks will test it

----

it almost did it 

  // Not compiled, not tested.

union toShift
{
    int  vsigned;
    uint vnotsigned;
};

toShift x;
x.vsigned=-32;
   for(int i=0;i<8;i++){
   int sh=x.vnotsigned>>i;
   Print(IntegerToString(x.vsigned)+" >> "+IntegerToString(i)+" = "+IntegerToString(sh));
   } 

[Alain Verleyen]

Lorentzos Roussos #:

also , off topic , shouldn't (-32)>>7 be zero ?

No. It can never be 0 with a negative number, as 1 are filled on the left side, so the "end" of the shift is always -1.

Read about binary 2's complement for a better understanding.

https://en.wikipedia.org/wiki/Two%27s_complement

[Alain Verleyen]

Lorentzos Roussos #:

thanks will test it

----

it almost did it 

Yeah, for sure the >>0 is a bit special. You will certainly find how to solve it.

[Fernando Carreiro]

Alain Verleyen #: There is no unsigned right shift in mql5. You need to be creative.

Huh? ... " If the value to shift is of the unsigned type, the logical right shift is made, "

[Lorentzos Roussos]

Alain Verleyen #:
Yeah, for sure the >>0 is a bit special. You will certainly find how to solve it.

will do