C#-এ Stack.Peek() মেথডটি Stack-এর উপরের (top) এলিমেন্টটি রিটার্ন করে কিন্তু এটি Stack থেকে সরিয়ে দেয় না। Stack LIFO (Last In, First Out) নীতিতে কাজ করে।
সিনট্যাক্স (Syntax)
public virtual object Peek ();
উদাহরণ ১: স্ট্রিং Stack-এ Peek() ব্যবহার
using System;
using System.Collections;
public class Demo {
public static void Main() {
Stack stack = new Stack();
stack.Push("Inspiron");
stack.Push("Alienware");
stack.Push("Projectors");
stack.Push("Monitors");
stack.Push("XPS");
stack.Push("Laptop");
stack.Push("Notebook");
Console.WriteLine("Stack elements...");
foreach(string val in stack) {
Console.WriteLine(val);
}
Console.WriteLine("Count of elements = " + stack.Count);
Console.WriteLine("Element at the top = " + stack.Peek());
stack.Push("Ultrabook");
stack.Push("Cameras");
stack.Push("Keyboards");
Console.WriteLine("\nStack elements...updated");
foreach(string val in stack) {
Console.WriteLine(val);
}
Console.WriteLine("Element at the top = " + stack.Peek());
Console.WriteLine("\nCount of elements (updated) = " + stack.Count);
stack.Clear();
Console.Write("Count of elements (updated) = " + stack.Count);
}
}
আউটপুট
Stack elements... Notebook Laptop XPS Monitors Projectors Alienware Inspiron Count of elements = 7 Element at the top = Notebook Stack elements...updated Keyboards Cameras Ultrabook Notebook Laptop XPS Monitors Projectors Alienware Inspiron Element at the top = Keyboards Count of elements (updated) = 10 Count of elements (updated) = 0
উদাহরণ ২: Contains, Clone এবং Peek() একসাথে
using System;
using System.Collections;
public class Demo {
public static void Main() {
Stack stack = new Stack();
stack.Push("Inspiron");
stack.Push("Alienware");
stack.Push("Projectors");
stack.Push("Monitors");
stack.Push("XPS");
stack.Push("Laptop");
stack.Push("Notebook");
Console.WriteLine("Stack elements...");
foreach(string val in stack) {
Console.WriteLine(val);
}
Console.WriteLine("Count of elements = " + stack.Count);
Console.WriteLine("Element Speakers is the stack? = " + stack.Contains("Speakers"));
stack.Push("Headphone");
stack.Push("Keyboard");
stack.Push("Earphone");
Console.WriteLine("\nStack elements...updated");
foreach(string val in stack) {
Console.WriteLine(val);
}
Console.WriteLine("Count of elements (updated) = " + stack.Count);
Console.WriteLine("Element Alienware is the stack? = " + stack.Contains("Alienware"));
Stack stack2 = (Stack)stack.Clone();
Console.WriteLine("\nStack elements...cloned");
foreach(string val in stack2) {
Console.WriteLine(val);
}
Console.Write("Count of elements (updated) = " + stack2.Count);
Console.WriteLine("Top of the Stack = " + stack2.Peek());
}
}
আউটপুট
Stack elements... Notebook Laptop XPS Monitors Projectors Alienware Inspiron Count of elements = 7 Element at the top = Notebook Stack elements...updated Keyboards Cameras Ultrabook Notebook Laptop XPS Monitors Projectors Alienware Inspiron Element at the top = Keyboards Count of elements (updated) = 10 Count of elements (updated) = 0
মূল পয়েন্টস
Peek()মেথড Stack-এর টপ এলিমেন্টটি শুধু দেখে, সরিয়ে দেয় না।- যদি Stack খালি থাকে,
Peek()কল করলেInvalidOperationExceptionথ্রো করে। Pop()মেথড টপ এলিমেন্টটি রিটার্ন করে এবং সেটিকে Stack থেকে সরিয়ে দেয়।- পূর্বে
Clear()কল করা থাকলে Stack খালি থাকে, তাই Peek() এক্সেপশন থ্রো করবে।
