if/else, switch (แบบดั้งเดิม) และลูป: for, while, do, foreach

ภาพรวม

พื้นฐาน if/else

using System;

public class Program
{
  public static void Main(string[] args)
  {
    int temperature = 18;

    if (temperature >= 25)
    {
      Console.WriteLine("Warm");
    }
    else if (temperature >= 15)
    {
      Console.WriteLine("Mild");
    }
    else
    {
      Console.WriteLine("Cold");
    }
  }
}

switch แบบดั้งเดิม

using System;

public class Program
{
  public static void Main(string[] args)
  {
    int day = 3;

    switch (day)
    {
      case 1:
        Console.WriteLine("Mon");
        break;
      case 2:
        Console.WriteLine("Tue");
        break;
      case 3:
        Console.WriteLine("Wed");
        break;
      case 4:
        Console.WriteLine("Thu");
        break;
      case 5:
        Console.WriteLine("Fri");
        break;
      case 6:
      case 7:
        Console.WriteLine("Weekend");
        break;
      default:
        Console.WriteLine("Invalid");
        break;
    }
  }
}

วงวน for

using System;

public class Program
{
  public static void Main(string[] args)
  {
    int sum = 0;
    for (int i = 1; i <= 5; i = i + 1)
    {
      sum = sum + i;
    }
    Console.WriteLine("Sum 1..5 = " + sum);
  }
}

while และ do-while

using System;

public class Program
{
  public static void Main(string[] args)
  {
    // while: check before running
    int countdown = 3;
    while (countdown > 0)
    {
      Console.WriteLine(countdown);
      countdown = countdown - 1;
    }
    Console.WriteLine("Go!");

    // do-while: runs at least once
    int tries = 0;
    do
    {
      tries = tries + 1;
      Console.WriteLine("Attempt " + tries);
    } while (tries < 1);
  }
}

พื้นฐาน foreach

using System;
using System.Collections.Generic;

public class Program
{
  public static void Main(string[] args)
  {
    int total = 0;
    int[] nums = new int[] { 2, 4, 6 };

    foreach (int n in nums)
    {
      total = total + n;
    }
    Console.WriteLine("Total = " + total);

    // Works with collections too
    List<string> names = new List<string>();
    names.Add("Ada");
    names.Add("Alan");
    foreach (string s in names)
    {
      Console.WriteLine("Hi " + s);
    }
  }
}

ข้อเท็จจริงของ do-while

ทบทวน