a bit map in c++ - will unsigned int do the job?

Question

I'm afraid to admit, I haven't used C++ for a while now but i'm afraid I have to now, and I'm a bit rusty.
I need to have a bitmap, and I do care about performance, my bitmap size will be no longer then 25 bits.
I was thinking about using unsigned int, but I am afraid I do not remember how it is implemented in c/c++

Is unsigned int implemented as a regular binary number?
I am also open to any other suggestions for a bitmap.
thanks in advance for the help!

Answer 1

Use an std::bitset<25> from the header <bitset>. bitset can be indexed with [] and is a template, so it likely expands to just an unsigned int (or equivalent) with all operations inlined.

Answer 2

Have you considered std::bitset from <bitset> header file?

Example:

#include <iostream>
#include <bitset>

int main() {
        std::bitset<25> bits(146);
        std::cout << bits << std::endl;

        //using operator[] to access individual bit manually!
        for(size_t i = 0 ; i < bits.size() ; ++i)
           std::cout << bits[i] << " ";
        return 0;
}

Output:

0000000000000000010010010
0 1 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Note: bits[0] is the least significant bit, while bits[bits.size()-1] is the most significant bit!

Online demo : http://ideone.com/3sSF0

Answer 3

consider a bitset instead.

Answer 4

You should be able to use an integer type for a bit map, assuming it has enough bits for you.

However, there is a <bitset> in the standard library.