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Questions tagged [bitsets]

DO NOT USE: use bitset instead

18 questions
73
votes
8 answers

boolean[] vs. BitSet: Which is more efficient?

What is more efficient in terms of memory and CPU usage — an array of booleans or a BitSet? Specific BitSet methods are not used, only get/set/clear (==, =, Arrays.fill respectively for an array).
Maxim
16
votes
4 answers

When to use STL bitsets instead of separate variables?

In what situation would it be more appropriate for me to use a bitset (STL container) to manage a set of flags rather than having them declared as a number of separate (bool) variables? Will I get a significant performance gain if I used a bitset…
David
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3 answers

How to write a std::bitset template that works on 32 and 64-bit

Consider the following code template void foo(std::bitset bs) { /* whatever */ } int main() { bitset<8> bar; foo(bar); return 0; } g++ complains about this on 64 bit because the <8> gets interpreted as an unsigned…
Tyler McHenry
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7
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1 answer

Setting boost dynamic_bitset from a string

Dynamic bitset I have a use case where i need to populate boost::dynamic_bitset , from a std::string buffer. Can you suggest as to how to go about this. So I need to come up with a function void populateBitSet (std::string &buffer,…
kal
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5
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1 answer

BitSet memory usage in Scala

I would like to know what is the memory usage of BitSet in Scala.For example, if I do: var bitArray:BitSet=new BitSet(10) bitArray.add(0) bitArray.add(2) bitArray.add(4) bitArray.add(6) bitArray.add(8) How does that compare with and…
Skuge
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4
votes
4 answers

Easy way to convert a string of 0's and 1's into a character? Plain C

I'm doing a steganography project where I read in bytes from a ppm file and add the least significant bit to an array. So once 8 bytes are read in, I would have 8 bits in my array, which should equal some character in a hidden message. Is there an…
Anon
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2
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5 answers

flag bitset, avoiding collisions, C

I've got a flag-holding integer that has an existing set of possible flags: #define MAIL_ADDR_FROM 0x0001 /* address field contains the from address */ #define MAIL_ADDR_TO 0x0002 /* address field contains the to address */ #define MAIL_SEEN …
VMills
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2
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1 answer

STL bitset problem

I have a template class "HEADER_FILE" that has a variable bitset<> using std::bitset; using std::bitset; template class Foo{ bitset bits; }; i cannot use using namespace std; in header…
Ashish Negi
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2
votes
1 answer

Social graphs using bitsets

I came across the following line in an article where this internet technology firm talks about how they baked social features into their application: Apache Thrift, Krati Data Store, JavaEWAH Compressed Bitmaps and JRuby forms the part of our…
Varun Jain
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2
votes
1 answer

Why a C++ bitset initialized using an string is reversed?

For the first time, I initialized a bit set using a string and found out that the bits are stored in reverse order, i.e.: bitset<3> test(string("001")); then the bits are stored as bellow: test[0] = 1 test[1] = 0 test[2] = 0 I am not…
dahma
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1
vote
2 answers

is it possible to convert bitset<8> to an array of characters of integers?

I have bitset<8> v8 and its value is something like "11001101", something in binary, how can we convert it to an array of characters or integers in c++?
bijlikamasla
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6 answers

How best to implement BCD as an exercise?

I'm a beginner (self-learning) programmer learning C++, and recently I decided to implement a binary-coded decimal (BCD) class as an exercise, and so I could handle very large numbers on Project Euler. I'd like to do it as basically as possible,…
Skilldrick
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1
vote
1 answer

How do I change the value of a dynamic_bitset?

I am using C++ boost's dynamic_bitset. I have already allocated a variable and I just want to change its value - to construct it anew from an 'unsigned long' like from the constructor, but I don't want to allocate the memory again or to create a…
R S
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1
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1 answer

C++ convert 8 bit bitset to unsigned long, VS 2010 - not working

Below code works first two times thru and then on the third time the convert to ulong fails and gives me a 0XCF instead of 0xF3. Any idea what the problem is?? Seems like a bug in the VS 2010 to_long. binary '11110011' should convert to Hex F3! …
Duffy
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2 answers

Java multi-bit / compact small integer array

I am working on implementing some bloom filter variants, and a very useful data structure for this would be a compact multi-bit array; that is, an array where each element is a compact integer of around 4 bits. Space efficiency is of the utmost…
Aniket Schneider
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