davidon

Frequently Used Git Worktree Commands

Basic Operations

git worktree add <path> <branch>         # Create worktree for a branch that already exists in the repo
git worktree add -b <new-branch> <path>  # Create worktree with new branch
git worktree list                        # List all worktrees
git worktree remove <path>               # Remove a worktree

davidon

Null Object Pattern in PHP

Overview

The Null Object pattern replaces null return values with a special "do-nothing" object that shares the same interface as the real object. This eliminates the need for null checks at every call site and prevents "Call to a member function on null" fatal errors.

When to use it

davidon

Front End Knowledge Base

A collection of dev notes and Q&A on web development topics.

Contents

File	Topic
Git-conventional-commits.md	Conventional Commits — feat, fix, and friends
JS-worklets-vs-main-thread.md	Worklets vs Main Thread
Tool-copilot-edit-vs-plan-vs-agent.md	GitHub Copilot Modes — Edit vs Plan vs Agent
Web-chrome-third-party-cookies.md	Chrome & Third-Party Cookies (2025)
Web-storage-comparison.md	sessionStorage vs localStorage vs Cache Storage vs Shared Storage

davidon

Reducer-LocalStorage-Tasks-React

A Pen by davidon dan on CodePen.

License.

davidon

App-LocalStorage-Tasks-React

A Pen by davidon dan on CodePen.

License.

davidon

using System.IO;
using System;

class Solution {

    // Complete the hourglassSum function below.
    static int hourglassSum(int[][] arr) {
        int[] sum = new int[16];
        int k = 0;
        for (int i = 0; i <= 3; i++)

davidon

public function format_phone_number($S) {
    $S = str_replace(' ', '', $S);
    $S = str_replace('-', '', $S);
    $len = strlen($S);
    $num_groups = floor($len / 3);
    $remain = $len % 3;

    if ($num_groups >= 1 && $remain == 1) {
        $num_groups -= 1;
        $remain += 3;   //4

davidon

#include "pch.h"
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <time.h>

using namespace std;

int get_max_profit(vector<int> prices);

davidon

<?php
//this is to get the max gap in an array supposing gap can only be a later number minus a former number

$stock_prices_yesterday = [25, 7, 5, 8, 11, 9];
$m_profit = GetMaxProfit($stock_prices_yesterday);
# returns 6 (buying for $5 and selling for $11)
print "1st:the most profit should be 6: {$m_profit}";

$stock_prices_yesterday = [10, 7, 11, 5, 8, 9];
$m_profit = GetMaxProfit($stock_prices_yesterday);

davidon

<?php
// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    // write your code in PHP7.0
    $arr_checker = range(1, 100000);

    $A = array_unique($A, SORT_NUMERIC );
    sort($A);