What does << mean in Ruby?

It can have 3 distinct meanings: ‘<<‘ as an ordinary method In most cases ‘<<‘ is a method defined like the rest of them, in your case it means “add to the end of this array” (see also here). That’s in your particular case, but there are also a lot of other occasions where you’ll encounter … Read more

Understanding NumPy’s einsum

(Note: this answer is based on a short blog post about einsum I wrote a while ago.) What does einsum do? Imagine that we have two multi-dimensional arrays, A and B. Now let’s suppose we want to… multiply A with B in a particular way to create new array of products; and then maybe sum this new array along particular axes; and then maybe transpose the axes of the new … Read more

Return char[]/string from a function

Notice you’re not dynamically allocating the variable, which pretty much means the data inside str, in your function, will be lost by the end of the function. You should have: Then, when you call the function, the type of the variable that will receive the data must match that of the function return. So, you should … Read more

Are arrays passed by value or passed by reference in Java?

Your question is based on a false premise. Arrays are not a primitive type in Java, but they are not objects either … “ In fact, all arrays in Java are objects1. Every Java array type has java.lang.Object as its supertype, and inherits the implementation of all methods in the Object API. … so are they passed by value or by … Read more

How to find the size of an int[]?

Try this: Because this question is tagged C++, it is always recommended to use std::vector in C++ rather than using conventional C-style arrays. An array-type is implicitly converted into a pointer-type when you pass it to a function. Have a look at this. In order to correctly print the sizeof an array inside any function, pass the array by reference to that … Read more

Make list of arrays in python

The above 2 lines doesn’t work the way you expect. append() function of list doesn’t return anything. It adds data at the end of the list object through which the append() was called. So final_array & final_direction will be None. I think you just need to append data to final_array & final_direction. Like this

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