There is a big misunderstanding here: You are comparing vectors with different semantics. It’s like asking which is faster, a glass of water or a banana. If you think about using a vector of pointers, std::vector<T*>, you need to be aware that you are using manual memory management. It might be faster in some use-cases, … Read more
There are a few ways to solve this, but I believe this should work: std::vector<std::vector<int>> vec2D; int index = -1; // Identify the indices of the position vector and use that to identify the // correct indices of the vec. for (int i = 0; i != position.size(); ++i) { // if the value at … Read more
In C++, using malloc the way you are using it is undefined behavior, as it does not perform object initialization, which means that it’s not calling the vector’s constructor (but there are other things that are not done, as initializing the vtable if there was one, for example). In your example, you should use new: … Read more
A three dimensional vector follows the same format that a 2 dimension vector has. If A, B, C … are defined as std::vector<std::vector<double> > A (6,std::vector<double>(6)); Then their type is std::vector<std::vector<double> >. To create a vector that will hold 8 of those then you need to use std::vector<std::vector<std::vector<double>>> someName(8); If you want to have the … Read more
Removing the two dashed lines in front of delete[] * it; solved the problem. 1 solved Reuse vector in loop outputs “Killed” after few iteration [closed]
You don’t have to use auto if you don’t want to, but you can of course. The type returned by std::vector<int>::begin() and std::vector<int>::end() is a std:vector<int>::iterator (or std:vector<int>::const_iterator, depending on context), it is not an int. You could as well have written this instead: for(vector<int>::iterator it=vect1.begin(); it<vect1.end();it++){ cout<<*it<<endl; } or for(vector<int>::const_iterator it=vect1.begin(); it<vect1.end();it++){ cout<<*it<<endl; } … Read more
The declaration std::vector<int> * ids; says that this is a pointer to either a single object of type std::vector<int> or to (the first element of) an array of that type. The fact that operator[] is used on it in the member function shows that the second is the case. Applying operator[] to a pointer (as … Read more
I think you need: df[‘features’] = df.values.tolist() print(df) Atr1 Atr2 features 0 1 A [1, A] 1 2 B [2, B] 2 4 C [4, C] If you have multiple columns and want to select particular columns then: df = pd.DataFrame({“Atr1″:[1,2,4],”Atr2″:[‘A’,’B’,’C’],”Atr3”:[‘x’,’y’,’z’]}) print(df) Atr1 Atr2 Atr3 0 1 A x 1 2 B y 2 4 … Read more
Simply use a new local variable inside your reading loop like this: while(stream >> token) { if(token == “#define”) { constantVariable addconstant; stream >> token; addconstant.constantName = token; stream >> token; addconstant.constantValue = token; constant.push_back(addconstant); } } But take care with checking the input stream. It should not be done as easy as you did … Read more
The answer can be read in the C++ reference. Here you can read that no boundary check will be done and no new element will be inserted. You simply have undefined behaviour. So, in moredetail: using an index operator with an index bigger than the size of the vector, will not increase the size of … Read more
Introduction This question is related to the use of vectors in programming. A vector is a data structure that stores a collection of elements, and it is often used in programming languages such as C++ and Java. The question is whether it is possible to access a location in a vector which has not been … Read more
The problem is that in the DeckOfCards class, the deck vector is never added to, so it’s empty. In the constructor, assign newDeck to deck: deck = newDeck; There is also another problem in the constructor: You declare newDeck to contain 52 entries, but then you use push_back to add new entries to the vector. … Read more
From the error message you provided it looks like you need to change the arguments of your operator == function from Myclass & to const Myclass &. solved C++ Constructor and vector, iterator
OK, so assuming you want to store the results in c, with dims 256, 50, do something like: for(int i = 0; i < 256; ++i) for(int j = 0; j < 55; ++j) { c[i][j] = compute_correlation(matrixA, i, matrixB, j); } with compute_correlation a simple for loop that will compute the value according to … Read more
You could – after skipping the line count – read in each individual character and compare it to ‘0’ or ‘1’. See the following code: int main() { vector<bool> bits; ifstream f(DATAFILE); if (f.is_open()) { int dummy; f >> dummy; char c; while (f >> c) { if (c == ‘1’) { bits.push_back(true); } else … Read more