count 1 in string

[thomas]

I have a list of strings composed of only 0 and 1, like
0000100001 1000010000, ....
They all have the same length.
Now they are stored in a vector of strings.
I want to calculate count(string1 xor string2).

for example:
1010, 0101 -xor- 1111 -- 4 (four 1s in the result string)
1111, 0000 -xor- 0000 -- 0

I can do it by string comparing, but I think it's really ugly.
And I do think there must be some easy and simple method, but I don't
know how.
Can you help me?

[Lionel B]

On Fri, 30 May 2008 05:38:32 -0700, thomas wrote:

I have a list of strings composed of only 0 and 1, like 0000100001
1000010000, ....
They all have the same length.
Now they are stored in a vector of strings. I want to calculate
count(string1 xor string2).

for example:
1010, 0101 -xor- 1111 -- 4 (four 1s in the result string) 1111,
0000 -xor- 0000 -- 0

I can do it by string comparing, but I think it's really ugly. And I do
think there must be some easy and simple method, but I don't know how.
Can you help me?

Consider using the std::bitset container, which represents a (fixed
length) sequence of bits. It supports basic logical operations (including
xor), bit counting and lots more. It can also be converted easily to and
from a character string representation.

--
Lionel B

[Victor Bazarov]

thomas wrote:

I have a list of strings composed of only 0 and 1, like
0000100001 1000010000, ....
They all have the same length.
Now they are stored in a vector of strings.
I want to calculate count(string1 xor string2).

for example:
1010, 0101 -xor- 1111 -- 4 (four 1s in the result string)
1111, 0000 -xor- 0000 -- 0

Uh... 1111 ^ 0000 =1111, unless you're using some funky definition of
xor.

I can do it by string comparing, but I think it's really ugly.
And I do think there must be some easy and simple method, but I don't
know how.
Can you help me?

If the strings are of the same length, you can do the accumulate of the
result of converting each char into a number (by subtracting '0', the
symbol "zero") and XORing those. Basically it'll be a loop o'er the
size of the string (using the iterators)... Simpler? Convert each into
a number and then xor those and then count the bits in the result (find
the algo on the 'net).

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[thomas]

>
Uh... *1111 ^ 0000 =1111, unless you're using some funky definition of
* xor.

that's a typo, I meant 1111 ^ 0000 -1111, :)

If the strings are of the same length, you can do the accumulate of the
result of converting each char into a number (by subtracting '0', the
symbol "zero") and XORing those. *Basically it'll be a loop o'er the
size of the string (using the iterators)... *Simpler? *Convert each into
a number and then xor those and then count the bits in the result (find
the algo on the 'net).

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Eric Pruneau]

"Lionel B" <[e-mail] a écrit dans le message de news:
g1**********@so uth.jnrs.ja.net ...

On Fri, 30 May 2008 05:38:32 -0700, thomas wrote:

>I have a list of strings composed of only 0 and 1, like 0000100001
1000010000, ....
They all have the same length.
Now they are stored in a vector of strings. I want to calculate
count(string 1 xor string2).

for example:
1010, 0101 -xor- 1111 -- 4 (four 1s in the result string) 1111,
0000 -xor- 0000 -- 0

I can do it by string comparing, but I think it's really ugly. And I do
think there must be some easy and simple method, but I don't know how.
Can you help me?

Consider using the std::bitset container, which represents a (fixed
length) sequence of bits. It supports basic logical operations (including
xor), bit counting and lots more. It can also be converted easily to and
from a character string representation.

--
Lionel B

Suppose you have
string s1("1010");
string s2("0101");

you can do:
bitset<4b1(s1);
bitset<4b2(s2);
bitset<4bxor = b1 ^ b2;
size_t count = bxor.count();