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Page 432: Bitset example does not pass tests. The bit order tests in it are backwards. #104

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WraithGlade opened this issue Jan 11, 2020 · 1 comment

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@WraithGlade
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@WraithGlade WraithGlade commented Jan 11, 2020

The code in the book looks like this:

TEST_CASE("std::bitset supports integer initialization") 
{ 
	std::bitset<4> bs(0b0101);
	
	REQUIRE_FALSE(bs[0]);
	REQUIRE(bs[1]);
	REQUIRE_FALSE(bs[2]);
	REQUIRE(bs[3]);
}

But the code needed to actually pass the test is this:

TEST_CASE("std::bitset supports integer initialization") 
{ 
	std::bitset<4> bs(0b0101);
	
	REQUIRE(bs[0]);
	REQUIRE_FALSE(bs[1]);
	REQUIRE(bs[2]);
	REQUIRE_FALSE(bs[3]);
}

The original code tests the bits in human reading order, but the passing test requires them to instead be ordered in least-significant to most-significant bit order.

Perhaps you accidentally forgot to compile this example.

Alternatively, I suppose a bit ordering difference is also conceivable, although I doubt it. I'm on a 64-bit version of Windows 7, running Visual Studio C++ 2019, in case that's relevant in that case.

(Also, as usual, I'm on the Kindle ebook version of the book.)

@JLospinoso

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@JLospinoso JLospinoso commented Jan 21, 2020

Thanks, @WraithGlade! I specifically remember fixing this during copyedit. Hmm...

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