Bitvector function Z3
来源： https://stackoverflow.com/questions/59702727/bitvector-function-z3
bitvector
Why isn't vector<bool> a STL container?
问题 Item 18 of Scott Meyers's book Effective STL: 50 Specific Ways to Improve Your Use of the Standard Template Library says to avoid vector <bool> as it's not an STL container and it doesn't really hold bool s. The following code: vector <bool> v; bool *pb =&v[0]; will not compile, violating a requirement of STL containers. Error: cannot convert 'std::vector<bool>::reference* {aka std::_Bit_reference*}' to 'bool*' in initialization vector<T>::operator [] return type is supposed to be T& , but
When should I use a BitVector32?
问题 I am working on a project where at a certain moment I need to show for one month which days are still available. There is a function that calculates which days are available. My colleagues said:"Oh we know, you should return a BitVector32. That's the most efficient when working with a list of booleans." I would have used a List<bool> or something like that. A BitVector32 seems to me to be something for low level stuff when you are actually working with bits. So, the question is. Should you
C++11 vector<bool> performance issue (with code example)
问题 I notice that vector is much slower than bool array when running the following code. int main() { int count = 0; int n = 1500000; // slower with c++ vector<bool> /*vector<bool> isPrime; isPrime.reserve(n); isPrime.assign(n, true); */ // faster with bool array bool* isPrime = new bool[n]; for (int i = 0; i < n; ++i) isPrime[i] = true; for (int i = 2; i< n; ++i) { if (isPrime[i]) count++; for (int j =2; i*j < n; ++j ) isPrime[i*j] = false; } cout << count << endl; return 0; } Is there some way
How do I convert a SQL Server 'Int' field to 'BitVector32' within my C# program?
问题 Total beginner jumping in the deep end. This is my first post here. I'm a mainframe programmer trying to join the 1990's and learn some object oriented programming(which is currently greek to me). Please forgive my elementary explanation below. I'm developing an application which needs to keep an availability calendar for people on a Sql Server DB. Since I could have tens of thousands (or more) rows, I was hoping to be as efficient as possible and not waste space. Being totally green to C#, I
Are std::fill, std::copy specialized for std::vector<bool>?
问题 When thinking about this question I start to wondering if std::copy() and/or std::fill are specialized (I really mean optimized) for std::vector<bool> . Is this required by C++ standard or, perhaps, it is common approach by C++ std library vendors? Simple speaking, I wonder to know if the following code: std::vector<bool> v(10, false); std::fill(v.begin(), v.end(), true); is in any way better/different than that: std::vector<bool> v(10, false); for (auto it = v.begin(); it != v.end(); ++it)
Bit Vector tactic leads to exit code 139 in Z3Py
问题 This is a simple bit vector problem: import z3 s = z3.Tactic('bv').solver() m = z3.Function('m', z3.BitVecSort(32), z3.BitVecSort(32)) a, b = z3.BitVecs('a b', 32) axioms = [ a == m(12432), z3.Not(a == b) ] s.add(axioms) print(s.check()) Python crashes with error code 139. Please note that, this is not my real problem, so I must use bit vector tactic in my project, though it doesn't have any problem with smt tactic or even qfbv tactic. 回答1: It seems to be a bug in 4.4.0. With 4.4.0 and Ubuntu
Z3 converting “small” BitVectors to Ints
问题 I know that both bv2int and int2bv are handled as uninterpreted functions in Z3. Still, I am looking for a best practice in solving the following problem: given a "small" (< 10 bits) bitvector index, how to efficiently cast it to Int, and use in queries like this one: (declare-const s String) (declare-const someInt Int) (declare-const someBitVec10 (_ BitVec 10)) (assert (= s "74g\x00!!#2#$$")) ;(assert (str.in.re (str.at s someBitVec10) (re.range "a" "z"))) ( assert (str.in.re (str.at s
When should I use a BitVector32?
I am working on a project where at a certain moment I need to show for one month which days are still available. There is a function that calculates which days are available. My colleagues said:"Oh we know, you should return a BitVector32 . That's the most efficient when working with a list of booleans." I would have used a List<bool> or something like that. A BitVector32 seems to me to be something for low level stuff when you are actually working with bits. So, the question is. Should you use the BitVector32 whenever you need some list of booleans with less than 32 items or should you only
Determining a string has all unique characters without using additional data structures and without the lowercase characters assumption
问题 This is one of the questions in the Cracking the Coding Interview book by Gayle Laakmann McDowell: Implement an algorithm to determine if a string has all unique characters. What if you can not use additional data structures? The author wrote: We can reduce our space usage a little bit by using a bit vector. We will assume, in the below code, that the string is only lower case 'a' through 'z' . This will allow us to use just a single int. The author has this implementation: public static