You can use the following condition:
(myvector.end() == std::find(myvector.begin(), myvector.end(), true))
Obviously, internally, this loops over all values.
The alternative (which really should avoid looping) is to override all write-access functions, and keep track of whether true
has ever been written to your vector.
UPDATE
Lie Ryan's comments below describe a more robust method of doing this, based on the same principle.
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