Re: [Boost-users] generate structs with all combinations of members from a given struct

On 01/30/10 01:41, OvermindDL1 wrote:

On Sat, Jan 30, 2010 at 12:35 AM, joel falcou wrote:

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OvermindDL1 wrote:

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Or make a fusion function called like permutation or so?

It's more than permuttion, it's combination but yeah that's the idea.

Er, yeah, whatever the word was, I have been up for near 24 hours. >.>

The OP said:

There are 15 of these, which is 2^4 -1, where 4 is the number of members in params.

Isn't 2^4 - 1 the number of non-empty subsets of: {field1, field2, field3. field4} ? Now, for r fields, the number of combinations of r fields from a set of n fields is: C(n,r) = (n!/(r!(n-r)!) Summing up for r=1..n gives: C(n,1)+C(n,2)+...+C(n,n) which is 2^n-1 (according to a textbook of mine), as the OP claimed.