bitwise OR on strings

How can i do a Bitwise OR on strings?

A:
10001
01010
------
11011

Why on strings? T开发者_开发问答he Bits can have length of 40-50.Maybe this could be problematic on int ? Any Ideas ?

I would say std::bitset is more than enough for your situation, but for more flexibility you can use boost::dynamic_bitset. Here is an example on std::bitset:

const size_t N = 64;
string a_str = "10001", b_str = "01010";
bitset<N> a(a_str), b(b_str);
bitset<N> c = a | b;

cout << c;

You should take a look at the C++ std::bitset class, which does exactly what you want.

For each char:

char result = (a - '0') | (b - '0') + '0';

Where a and b are two chars with ascii character 0 or 1 in them.

Why not just use a vector of int values? Doesn't the bitset still use a byte per bit?

You can also use a vector of bool values, but this is also implementation specific.

Depending on whether you need storage efficiency or speed (or the utility of container methods that a couple of these approaches lack) you might profile to decide which approach to use.

This is similar to Andreas Brinck's answer, only it returns a full output string and can compare strings of different (arbitrary) lengths.

Example in C# (not near c++ compiler right now), but it should be simple to convert it to a language of your choice.

public static string BitwiseOr(string input1, string input2)
{
    char[] inarr1 = (char[])input1.ToCharArray().Reverse().ToArray();
    char[] inarr2 = (char[])input2.ToCharArray().Reverse().ToArray();
    char[] outarr = new char[input1.Length > input2.Length ? input1.Length : input2.Length];

    for (int i = 0; i < outarr.Length ; i++)
    {
        char c1 = i < input1.Length ? inarr1[i] : '0';
        char c2 = i < input2.Length ? inarr2[i] : '0';
        outarr[i] = (char)((c1 - '0') | (c2 - '0') + '0');
    }

    return new string((char[])outarr.Reverse().ToArray());
}

Of course this is only valid if you really need it to be in a string, if not you should (as suggested in other answers) use a vector or similar data type.