ภาพรวม
foreach ใช้วนลูปอ่านสมาชิกอาร์เรย์ตามลำดับ ไม่ต้องจัดการดัชนีเอง ยังมีเมธอดสแตติก Array.Exists สำหรับตรวจสอบเงื่อนไข
ตัวอย่างที่ 1: วนลูปอาร์เรย์สตริงและใช้ Array.Exists
using System;
public class Demo
{
public static void Main()
{
string[] products = new string[] { "Electronics", "Accessories", "Clothing", "Toys", "Clothing", "Furniture" };
Console.WriteLine("Products list...");
foreach (string s in products)
{
Console.WriteLine(s);
}
Console.WriteLine("Is the products Accessories in the array? = {0}", Array.Exists(products, ele => ele == "Accessories"));
Console.WriteLine("Is the products Stationery in the array? = {0}", Array.Exists(products, ele => ele == "Stationery"));
Console.WriteLine("\nOne or more products begin with the letter 'C'? = {0}", Array.Exists(products, ele => ele.StartsWith("C")));
Console.WriteLine("One or more planets begin with 'D'? = {0}", Array.Exists(products, ele => ele.StartsWith("D")));
Console.WriteLine("One or more products begin with the letter 'T'? = {0}", Array.Exists(products, ele => ele.StartsWith("T")));
Console.WriteLine("One or more planets begin with 'E'? = {0}", Array.Exists(products, ele => ele.StartsWith("E")));
Console.WriteLine("Is the array having fixed size? = " + products.IsFixedSize);
}
}
ผลลัพธ์
Products list... Electronics Accessories Clothing Toys Clothing Furniture Is the products Accessories in the array? = True Is the products Stationery in the array? = False One or more products begin with the letter 'C'? = True One or more planets begin with 'D'? = False One or more products begin with the letter 'T'? = True One or more planets begin with 'E'? = True Is the array having fixed size? = True
ตัวอย่างที่ 2: เปรียบเทียบอาร์เรย์สองตัว
using System;
public class Demo
{
public static void Main()
{
String[] strArr1 = new String[3] { "John", "Jacob", "Tim" };
String[] strArr2 = new String[3] { "Tom", "Brad", "Bradley" };
Console.WriteLine("First String array...");
foreach (string val in strArr1)
{
Console.WriteLine(val);
}
Console.WriteLine("Second String array...");
foreach (string val in strArr2)
{
Console.WriteLine(val);
}
Console.WriteLine("Are both the array objects equal? = " + strArr1.Equals(strArr2));
}
}
ผลลัพธ์
First String array... John Jacob Tim Second String array... Tom Brad Bradley Are both the array objects equal? = False
สรุป
foreachอ่านอย่างเดียว ไม่สามารถแก้ไขสมาชิกได้Array.Existsใช้ delegate/predicate ตรวจสอบเงื่อนไขEqualsของอาร์เรย์เปรียบเทียบ reference ไม่ใช่เนื้อหา
