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Why is it not possible to exchange the position of array name and index in swift like C (a[i] == i[a])?

By : Kendra
Date : September 15 2020, 10:00 PM
this one helps. The reason: arrays are not first-class data types in C, but in other languages they are.
Because C doesn't support arrays as full native types, array access devolves into pointer math, so arr[ix] is defined by the language to be *(arr + ix), which is the same as *(ix + arr) plus the curious ix[arr] as all being exactly equivalent.
code :
// what is printed?
#include <stdio.h>

int a[] = { 4, 2, 0, 1, 3 };

int main()
    int i = 1[a][a][a][a];  // HUH?

    printf("i = %d\n", i);

    return 0;

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Exchange position of 2 array elements in Python

By : Phil Hack
Date : March 29 2020, 07:55 AM
seems to work fine Is there any easy way to exchange the position of 2 elements - or better yet, n elements - in an array? , try
code :
>>> chromo[gene1Pos], chromo[gene2Pos] = chromo[gene2Pos], chromo[gene1Pos]

how to exchange position of array terms use numpy in python?

By : Pierre
Date : March 29 2020, 07:55 AM
this will help , Those rows can be sliced with:
code :
In [1418]: a[:,2,:]
array([[ 4,  5],
       [10, 11]])
In [1419]: a[::-1,2,:]
array([[10, 11],
       [ 4,  5]])
In [1420]: a[:,2,:] = a[::-1,2,:]
In [1421]: a
array([[[ 0,  1],
        [ 2,  3],
        [10, 11]],

       [[ 6,  7],
        [ 8,  9],
        [ 4,  5]]])

is it possible to get the index (String.Index) value from the cursor position of a UITextView element in Swift?

By : Colin.Z
Date : March 29 2020, 07:55 AM
hop of those help? You can get the selected range offset from the beginning of your document to the start of the selected range and use that offset to get your string index as follow:
code :
extension UITextView {
    var cursorOffset: Int? {
        guard let range = selectedTextRange else { return nil }
        return offset(from: beginningOfDocument, to: range.start)
    var cursorIndex: String.Index? {
            let location = cursorOffset,
            case let length = text.utf16.count-location
        else { return nil }
        return Range(.init(location: location, length: length), in: text)?.lowerBound
    var cursorDistance: Int? {
        guard let cursorIndex = cursorIndex else { return nil }
        return text.distance(from: text.startIndex, to: cursorIndex)
class ViewController: UIViewController, UITextViewDelegate {
    @IBOutlet weak var textView: UITextView!
    override func viewDidLoad() {
        textView.delegate = self
    func textViewDidChangeSelection(_ textView: UITextView) {
        print("Cursor UTF16 Offset:",textView.cursorOffset ?? "")
        print("Cursor Index:", textView.cursorIndex ?? "")
        print("Cursor distance:", textView.cursorDistance ?? "")

exchange string position using funcion in array of pointers

By : IAMADummy
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further code: , First declare as:

exchange array elements in Swift

By : diopas70
Date : March 29 2020, 07:55 AM
wish of those help I wrote a function to exchange the array elements. But it returns error: Playground execution failed: :21:5: error: '@lvalue $T8' is not identical to 'T' data[i] = data[j] ^ :22:5: error: '@lvalue $T5' is not identical to 'T' data[j] = temp ^ , You can simply do:
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