Details
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Bug
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Resolution: Fixed
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P2: Important
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6.7.0
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None
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Windows
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8ac57ff6b (dev), cb517bd2e (6.8), 05f0c6ca0 (6.7)
Description
To replicate:
QBitArray bitArrayAllOn(20, true); QBitArray bitArrayHalfAll(20, false); // Set every odd index to ON for (int i = 0; i < bitArrayHalfAll.size(); ++i) { bitArrayHalfAll.setBit(i, (i % 2)); } // Expect result not to change and be 10 on, 10 off. bitArrayHalfAll = bitArrayAllOn & bitArrayHalfAll; // Acutall result is size 20, on 15, off 5. qDebug() << "Size :" << bitArrayHalfAll.size(); qDebug() << "On count :" << bitArrayHalfAll.count(true); qDebug() << "Off count :" << bitArrayHalfAll.count(false); // Work around I found that might help narrow down the issue. bitArrayHalfAll.resize(bitArrayHalfAll.size()); // After resizing result is what is expected, size 20, 10 on, 10 off qDebug() << "Size :" << bitArrayHalfAll.size(); qDebug() << "On count :" << bitArrayHalfAll.count(true); qDebug() << "Off count :" << bitArrayHalfAll.count(false);
Output:
Size : 20 On count : 15 Off count : 5 Size : 20 On count : 10 Off count : 10
The above code creates two QBitArrays, one with all on bits and the other with half on.
When using bitwise & between the to arrays, we can see the result is incorrect. It should still have an on count on 10 out of 20 bits. This seems to be an issue with the classes internal size as calling resize on the bitarray fixes the result.