C# Collections MCQs

Question 1: Which of the following is a correct way to initialize an array?

• int[] arr = new int[5];
• int[] arr = new int[]{1, 2, 3, 4, 5};
• var arr = new int[5]{1, 2, 3, 4, 5};
• int[] arr = int[]{1, 2, 3, 4, 5};
• int[] arr = {1, 2, 3, 4, 5};
• var arr = {1, 2, 3, 4, 5};

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Question 2: Which of the following statement(s) are TRUE?

• Array is a value type.
• Array is a reference type.
• Array is a primitive type.
• None of the above.

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Question 3: Which of the following method returns the highest index of an array?

• GetLastIndex()
• GetUpperIndex()
• GetUpperBound()
• GetLength()

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Question 4: Which of the following array declaration is valid?

• int[] arr = new int[3];
• int[,] arr1 = new int[3,2];
• int[][,] arr2 = new int[3][,];
• All of the above

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Question 5: What will be the output of the following program?

public class Program
{
	public static void Main()
	{
		string[] strArr = {"Hello","World"};
  
  		object[] objArr = strArr;
		
		Console.Write(objArr[0]);
	}
}

• Hello
• World
• Compile-time error
• Runtime error

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Question 6: What will be the output of the following program?

using System;
using System.Collections.Generic;
		
public class Program
{
	public static void Main()
	{
		string[] strArr = {"Hello","World"};
        		
        IList<string> strList = strArr;
		IList<object> objList = strArr;

		Console.Write(strList[0] + objList[1]);
	}
}

• Compile-time error
• Runtime error
• Hello
• HelloWorld

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Question 7: What will be the output of the following program?

public class Program
{
	public static void Main()
	{
		int i = 3;
		int[] arr = new int[i] {10, 20, 30};

		Console.Write(arr[0]);
	}
}

• 10
• 0
• Compile-time error
• Runtime error

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Question 8: What will be the output of the following program?

public static void Main(string[] args)
{
	int[] arr = {1, 2, 3};
	display(arr);
	display(4,5,6);
}

static void display(params int[] arr){
	
	foreach(var i in arr)
		Console.Write(i);
}

• Compile-time error
• Runtime error
• 123
• 123456

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Question 9: Which of the following collection type will you use to hold values of different data types?

• SortedList
• Stack
• Queue
• ArrayList

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Question 10: Which of the following is LIFO (Last In First Out) collection?

• Array
• Dictionary
• Queue
• Stack

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