I would have had to vote against your proof-of-concept implementation had it been proposed. I fear it would break the following code, which I’m pretty sure I’ve seen in the wild at least once or twice over the past dozen years. namespace oops { struct foo { foo() : i(0) {} int i; void swap(foo& … Read more
Yes, this is perfectly safe to swap vectors of the same type. Vector under the hood is just a few pointers pointing to the data the vector uses and “end” of the sequence. When you call swap you just exchange those pointers between the vectors. You don’t need to worry that the vectors are the … Read more
Yes, it is possible. Assuming a and b have the same type, the example provided will work just fine. For example: a, b := “second”, “first” fmt.Println(a, b) // Prints “second first” b, a = a, b fmt.Println(a, b) // Prints “first second” Run sample on the playground This is both legal and idiomatic, so … Read more
I see you’re using numpy arrays. In that case, you can also do this: input_seq[[ix1, ix2]] = input_seq[[ix2, ix1]]
It is a matter of judgment. I will typically let std::swap do the job for prototyping code, but for release code write a custom swap. I can usually write a custom swap that is about twice as fast as 1 move construction + 2 move assignments + 1 resourceless destruction. However one may want to … Read more
For most classes, the default swap is fine, however, the default swap is not optimal in all cases. The most common example of this would be a class using the Pointer to Implementation idiom. Where as with the default swap a large amount of memory would get copied, is you specialized swap, you could speed … Read more
DuckDucking turned up this by Ken. Surprisingly, it’s even more concise and complete than Nikita’s answer. It retrieves column and row lengths implicitly within the guts of map(). function transpose(a) { return Object.keys(a[0]).map(function(c) { return a.map(function(r) { return r[c]; }); }); } console.log(transpose([ [1,2,3], [4,5,6], [7,8,9] ]));
Since String objects are immutable, going to a char[] via toCharArray, swapping the characters, then making a new String from char[] via the String(char[]) constructor would work. The following example swaps the first and second characters: String originalString = “abcde”; char[] c = originalString.toCharArray(); // Replace with a “swap” function, if desired: char temp = … Read more
The specialization of std::swap is now optional, but not deprecated. The rationale is performance. For prototyping code, and perhaps even for much shipping code, std::swap will be plenty fast. However if you’re in a situation where you need to eek out every little bit from your code, writing a custom swap can still be a … Read more