# UNIVERSAL CHEAT SHEET (Console & GUI)
===========================================================================
*/

using System;
using System.Collections.Generic; // Required for Lists
using System.Drawing;             // Required for GUI Colors
using System.Windows.Forms;       // Required for GUI Controls

// 1. BASIC PROGRAM STRUCTURE
namespace MyApp {
    class Program {
        static void Main(string[] args) {
            Console.WriteLine("Hello World!"); 
        }
    }
}

// 2. VARIABLES & DATA TYPES
int age = 25;                       // Whole numbers
double pi = 3.14;                   // Standard decimals
decimal price = 19.99m;             // Money (requires 'm')
string name = "Gemini";             // Text
bool isReady = true;                // True/False
var autoType = 50;                  // Compiler infers 'int'
const float Gravity = 9.8f;         // Constant (cannot change)

// 3. INPUT / OUTPUT & STRINGS
Console.Write("Enter text: ");
string input = Console.ReadLine();  // Get user input
Console.WriteLine($"Hi {input}!");  // String Interpolation ($)
string upper = input.ToUpper();     // Convert to uppercase
int length = input.Length;          // Get character count

// 4. MATH & COMPARISON
int sum = 10 + 2;                   // 12
int rem = 10 % 3;                   // 1 (Remainder)
bool check = (10 > 5);              // true
bool and = (true && false);         // false (AND)
bool or = (true || false);          // true (OR)

// 5. CONTROL FLOW (LOGIC)
if (age >= 18) {
    Console.WriteLine("Adult");
} else {
    Console.WriteLine("Minor");
}

switch (age) {
    case 21: Console.WriteLine("Legal"); break;
    default: Console.WriteLine("Other"); break;
}

// 6. LOOPS
for (int i = 0; i < 5; i++) {       // Run 5 times
    Console.WriteLine(i);
}

foreach (var item in myList) {      // Loop through collections
    Console.WriteLine(item);
}

while (isReady) {                   // Run while condition is true
    isReady = false; 
}

// 7. COLLECTIONS
int[] nums = {1, 2, 3};             // Fixed-size Array
List<string> list = new List<string>(); // Dynamic List
list.Add("Item");
list.Remove("Item");

// 8. METHODS (FUNCTIONS)
// Access | ReturnType | Name(Parameters)
public static int Square(int n) {
    return n * n;
}

// 9. CLASSES & OOP
class Animal {
    public string Species { get; set; } // Property
    public void MakeSound() {           // Method
        Console.WriteLine("Noise!");
    }
}
Animal myDog = new Animal();
myDog.Species = "Canine";

// 10. ERROR HANDLING
try {
    int zero = 0;
    int crash = 5 / zero;
} catch (Exception ex) {
    Console.WriteLine(ex.Message);
}

// ===========================================================================
// GUI BASICS (Windows Forms)
// ===========================================================================

/*
  COMMON CONTROLS:
  - Label (lbl): Displays text
  - TextBox (txt): User input field
  - Button (btn): Clickable action
  - ComboBox (cmb): Dropdown menu
*/

// GET/SET TEXT
string userText = txtInput.Text;    // Read from TextBox
lblStatus.Text = "Processing...";   // Write to Label

// BUTTON CLICK EVENT
private void btnSubmit_Click(object sender, EventArgs e) {
    MessageBox.Show("Hello!");      // Pop-up Alert
}

// UI STYLING & LOGIC
btnSubmit.Enabled = false;          // Gray out button
lblError.Visible = true;            // Show hidden label
this.BackColor = Color.LightBlue;   // Change window color

// MESSAGE BOX WITH LOGIC
DialogResult result = MessageBox.Show("Exit?", "Confirm", MessageBoxButtons.YesNo);
if (result == DialogResult.Yes) {
    Application.Exit();
}

// DROPDOWNS (ComboBox)
cmbOptions.Items.Add("Option A");   // Add item
string selected = cmbOptions.SelectedItem.ToString(); // Get selection