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    <p>Store the list of variables, and then sort them based on a custom comparison operator. For example:</p> <pre><code> // Ordering int* _ordering; // Variable template&lt;size_t T&gt; class Variable : public bitset&lt;T&gt; { private: char* _name; // A variable has a name. public: // Constructors Variable() :bitset&lt;T&gt;(), _name(NULL) {}; Variable(string bitstring, char* name) :bitset&lt;T&gt;(bitstring), _name(name) {}; // Name accessor char*&amp; name(void) {return _name;}; // Comparison operator bool operator&lt;(const Variable&lt;T&gt; &amp;rhs) const { for (int oidx=0; oidx&lt;T; oidx++) if (bitset&lt;T&gt;::test(_ordering[oidx])) { if (!rhs.test(_ordering[oidx])) // Left is bigger. return false; } else if (rhs.test(_ordering[oidx])) // Right is bigger. return true; // They match at all values. return false; } }; </code></pre> <p>Here is a quick and dirty main program that tests this with variables with 8 values.</p> <pre><code> #include &lt;iostream&gt; #include &lt;bitset&gt; #include &lt;stdlib.h&gt; #include &lt;stdio.h&gt; #include &lt;vector&gt; #include &lt;algorithm&gt; ... #define BITS 8 int main(int argc, char* argv[]) { int i; // Create the ordering based on the command line arguments _ordering = new int[BITS]; for (i=0; i&lt;BITS; i++) _ordering[i] = atoi(argv[i+1]); // Read in each variable int size=(argc-BITS-1)/2; vector&lt; Variable&lt;BITS&gt; &gt; variables; for (i=0; i&lt;size*2; i+=2) { cout &lt;&lt; "Creating bitset " &lt;&lt; argv[BITS+1+i]&lt;&lt;":"&lt;&lt;argv[BITS+2+i]&lt;&lt;endl; variables.push_back(Variable&lt;BITS&gt;(string(argv[BITS+i+1]), argv[BITS+i+2])); } // Display the variables for (i=0; i&lt;variables.size(); i++) cout &lt;&lt; variables[i] &lt;&lt; ":" &lt;&lt; variables[i].name() &lt;&lt; endl; // Sort them cout &lt;&lt; endl &lt;&lt; "Sorting..." &lt;&lt; endl; sort(variables.begin(), variables.end()); // Display again for (i=0; i&lt;variables.size(); i++) cout &lt;&lt; variables[i] &lt;&lt; ":" &lt;&lt; variables[i].name() &lt;&lt; endl; } </code></pre> <p>And here is the output:</p> <pre><code>$ ./bitsort 0 1 2 3 4 5 6 7 01 a 11 b 10 c 00 d Creating bitset 01:a Creating bitset 11:b Creating bitset 10:c Creating bitset 00:d 00000001:a 00000011:b 00000010:c 00000000:d Sorting... 00000000:d 00000010:c 00000001:a 00000011:b </code></pre>
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    1. POPermutation of binary variables and their value table
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    1. USTrenin
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    1. COSeems to work! nice! I did a solution for 4 bits with all the different cases (much work but very fast).
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      1. USJohan
    2. COYes. This is probably not the most efficient since the list is already sorted before we start - just not in the order we are expecting. Perhaps there is a way to use this information some how to perform a more efficient sort. Many generic sorting algorithms can take advantage of data that is partially sorted, so perhaps this is not something that needs further investigation.
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