Decimal to binary converter

Development Programming & Scripting C++
1

Hi guys,
Very simple question.
I want to do a game where you translate a decimal number to a binary one. Like you won points when you convert it well and u loose when u make errors.in the blueprint section, there is no section on binary to decimal converter. So how would I do it with bp or code?

2

In plain old C++


float f = 1234.567890;
unsigned char* bytes = (unsigned char *) &f;
cout << (int) bytes[3] << " " << (int) bytes[2] << " "  << (int) bytes[1] << " "  << (int) bytes[0] << endl;

You can get the individual bits from those bytes as well. The same works in reverse


unsigned char bytes[4] = {44, 82, 154, 68};
float *f = (float *) bytes;
cout << *f << endl;
3

You can check invidual bits this expression:


n & FMath::Pow(2,x)

n being a number and x being bit you check (not sure about 0 position, which should be first bit will work with pow… but there way to avoid it). How does it work? & is a AND gate operator, all power of 2 numbers and number 1 are 1 in invidual bit position in binery form ( 1=1, 2=10, 4=100, 8=1000) so if you do AND gate operation on series of bits againts 1 bit on specific position, it will return 0 if that invidual bit is 0. So in UE you can do this this way:



FString FMyFanctMath::BitsToString(int32 n){

       FString Bits;
       Bits.Reserve(FMath::FloorToInt(FMath::Sqrt(n))); //Reserveing space for string in memory FString won't rellocate string multiple times in process
       //We multiply by 2 until it's bigger then n where every bit will be 0 after that
       for(i = 1;i<n;i*2) {
         if(n & i) Bits.Append("1");
         else Bits.Append("0");
       }
       return Bits.Reverse() //We need to reverse bit order, so smallest is last
}

Obviuesly you can only present binery number in string, since any number is a number and can be presented in any form, UE4 presents number only in decimals, or else there also function for hex

C++14 allows to use binery form numbers in code, using “0b” prefix (same as “0x” for hex), but UE4 uses C++11 compiler mode if i’m not mistaken, so it won’t work in UE4

1 Like
4

Hi !! thx for fast reply! can u give me a personal email or a facebook so that i can give you more specificity…i promise it wont take that long!!!

5

ok so i guess its impossible to do that in blueprint right??thats what i thought…they should put it in the blueprint tho…cryengine 3 has the same problem!

6

No, it is possible in Blueprint i think, there is Bitwise AND node

Just do similar loop i showed you multiplaying i by 2 on each starting from 1, if result of AND is higher then 0 it means it has bit if 0 then no :slight_smile: remember you don’t need special loop node for that you can loop nodes together too, you just need to provide exit ot else you get infinite loop

7

thx man! ill read the doc!

8

Ok i just read it man. I might have read it too much fast but I think that this is what I need. I dont see the need of what you said by multiplying by two and using bolean operator…
what If i just use Random integer BP (to generate a random number) and I connect it to ‘‘tobyte(int)’’ and then connect to the UI blueprint to it appears on my screen? wouldnt it work?

9

That will convert it to byte, not bits. 1 byte = 8 bits = 2 hex digits. Byte type is uint8 and it can hold unsigned number in max 1 byte (8 bits) so max number it can have is 255 and can’t go below 0 as it is unsigned. Intiger is int32 which can hold signed number in 4 bytes (32 bits) which means it can hold max number of 2147483647 in both - and + direction as it is signed. Those are only 2 integer types that reflection system (and as result blueprint), in C++ you got 8, 16, 32 and 64 (on 64-bit CPUs only) sign and unsigned as well TBigInt which you can hold infinity (as memory size allows) big int, but blueprint don’t support it

10

I know but I want my number range to be between 0 and 255 so one byte…so i think that this bp is just fine

11

another question: how do i do so that one touch of the keyboard or (joystick) equals 0 and another 1?

12

Same as any other input

13

can you answer me as if i was a noob please. i just have 3 months in the engine :stuck_out_tongue:

14

try this one…

String str = “100”;
double j=0;
for(int i=0;i<str.length();i++){
if(str.charAt(i)== ‘1’){
j=j+ Math.pow(2,str.length()-1-i);
}
}

check…[)

15

If you need leading zeroes, like I did for sorting, you can use this (based on Shadowriver’s answer)

FString IntToBin(int32 n)
{
     FString bits;
     bits.Reserve(32);
     for (int32 i = 0; i < 32; i++)
     {
          bits.Append(n & (1 << i) ? "1" : "0");
     }
    return bits.Reverse();
}