creating an int from bits

[cppaddict]

Hi,

I am going to have a series of bit flags which I could store in an
array, or as a string ("10011001") , or any other way.

I want to be able to turn this series of bits into an int. I know C++
must have some class or built-in functionality for this, but my web
searching thus far hasn't found it. Can someone let me know what I
should use?

I am flexible on how to store the bits, so I'm taking suggestions for
that too. Ideally, I want whatever combination of bit-storage and
bit-to-int conversion mechanism is fastest.

Thanks for any ideas,
cpp

[Jacques Labuschagne]

cppaddict wrote:

Hi,

I am going to have a series of bit flags which I could store in an
array, or as a string ("10011001") , or any other way.

I want to be able to turn this series of bits into an int. I know C++
must have some class or built-in functionality for this, but my web
searching thus far hasn't found it. Can someone let me know what I
should use?

I am flexible on how to store the bits, so I'm taking suggestions for
that too. Ideally, I want whatever combination of bit-storage and
bit-to-int conversion mechanism is fastest.

How many bits? How do you want to handle the case where there are more
bits than can fit into an int?

Jacques.

[John Harrison]

"cppaddict" <he***@hello.co m> wrote in message
news:2v******** *************** *********@4ax.c om...

Hi,

I am going to have a series of bit flags which I could store in an
array, or as a string ("10011001") , or any other way.

I want to be able to turn this series of bits into an int. I know C++
must have some class or built-in functionality for this, but my web
searching thus far hasn't found it. Can someone let me know what I
should use?
bitset if you have a fixed number of bits. vector<bool> (I guess) if it is
variable.

I am flexible on how to store the bits, so I'm taking suggestions for
that too. Ideally, I want whatever combination of bit-storage and
bit-to-int conversion mechanism is fastest.

If I needed speed I think I would store the bits directly in an unsigned
int.

john

[cppaddict]

How many bits? How do you want to handle the case where there are more
bits than can fit into an int?

Jacques.

I will never have more than 18 bits.

[cppaddict]

If I needed speed I think I would store the bits directly in an unsigned
int.

John,

How would I accomplish this? Is there a way to set the individual
bits of an int? That's what I want to do.

Thanks,
cpp

[John Harrison]

"cppaddict" <he***@hello.co m> wrote in message
news:19******** *************** *********@4ax.c om...

If I needed speed I think I would store the bits directly in an unsigned
int.

John,

How would I accomplish this? Is there a way to set the individual
bits of an int? That's what I want to do.

Thanks,
cpp

inline void set_bit(unsigne d& bits, unsigned n)
{
bits |= (1 << n);
}

inline void clear_bit(unsig ned& bits, unsigned n)
{
bits &= ~(1 << n);
}

inline bool test_bit(unsign ed bits, unsigned n)
{
return (bits & (1 << n)) != 0;
}

Untested code.

john

[Jacques Labuschagne]

cppaddict wrote:

How many bits? How do you want to handle the case where there are more
bits than can fit into an int?

Jacques.

I will never have more than 18 bits.

Then John's answer is all you need, because an int usually has at least
32 bits.

[Kelvin]

"cppaddict" <he***@hello.co m> wrote in message
news:2v******** *************** *********@4ax.c om...

Hi,

I am going to have a series of bit flags which I could store in an
array, or as a string ("10011001") , or any other way.

I want to be able to turn this series of bits into an int. I know C++
must have some class or built-in functionality for this, but my web
searching thus far hasn't found it. Can someone let me know what I
should use?

I am flexible on how to store the bits, so I'm taking suggestions for
that too. Ideally, I want whatever combination of bit-storage and
bit-to-int conversion mechanism is fastest.

Thanks for any ideas,
cpp

if you want both readiblity and speed... i suggest you using hex numbers...
4 bits in one hex number... for example 0xF = 1111b ( note: the "b" here is
just to tell you it's a binary #, C++ deosnt support that...)

--
{ Kelvin@!!! }

[cppaddict]

inline void set_bit(unsigne d& bits, unsigned n)
{
bits |= (1 << n);
}

inline void clear_bit(unsig ned& bits, unsigned n)
{
bits &= ~(1 << n);
}

inline bool test_bit(unsign ed bits, unsigned n)
{
return (bits & (1 << n)) != 0;
}

Untested code.

john

Thanks John.

That's what I was looking for.

cpp

[Jeff Schwab]

John Harrison wrote:

"cppaddict" <he***@hello.co m> wrote in message
news:2v******** *************** *********@4ax.c om...

Hi,

I am going to have a series of bit flags which I could store in an
array, or as a string ("10011001") , or any other way.

I want to be able to turn this series of bits into an int. I know C++
must have some class or built-in functionality for this, but my web
searching thus far hasn't found it. Can someone let me know what I
should use?

bitset if you have a fixed number of bits. vector<bool> (I guess) if it is
variable.

I am flexible on how to store the bits, so I'm taking suggestions for
that too. Ideally, I want whatever combination of bit-storage and
bit-to-int conversion mechanism is fastest.

If I needed speed I think I would store the bits directly in an unsigned
int.

I thought you hated unsigned int's, and kinda thought they should be
removed from the language? (Not trying to rekindle any discussion on
the topic, just curious whether your opinion has changed.)