Impara Searching for Elements | Searching and Filtering Arrays

When working with arrays, you will often need to find out if a particular value exists or where it is located. Searching for elements in an array is a common operation in programming, especially when you want to locate data, validate input, or perform further actions based on the presence or position of a value. For example, you might want to check if a user's ID is already in use, or find the position of a specific score in a list. Understanding how to search arrays efficiently is an essential skill when working with collections of data.

Program.cs


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using System;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main()
        {
            int[] numbers = { 10, 25, 30, 47, 58 };
            int target = 30;
            int foundIndex = -1;

            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i] == target)
                {
                    foundIndex = i;
                    break;
                }
            }

            if (foundIndex != -1)
            {
                Console.WriteLine("Number " + target + " found at index " + foundIndex + ".");
            }
        }
    }
}

To find a specific value in an array, you use a loop to examine each element one by one. Inside the loop, an if statement checks whether the current element matches the value you are searching for. If a match is found, you can record the index and usually stop searching further, since you have found what you need. This approach is straightforward and works for arrays of any size or type.

Program.cs


              123456789101112131415161718192021222324252627282930313233
            
using System;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main()
        {
            int[] numbers = { 11, 22, 33, 44, 55 };
            int target = 99;
            int foundIndex = -1;

            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i] == target)
                {
                    foundIndex = i;
                    break;
                }
            }

            if (foundIndex != -1)
            {
                Console.WriteLine("Number " + target + " found at index " + foundIndex + ".");
            }
            else
            {
                Console.WriteLine("Number " + target + " not found in the array.");
            }
        }
    }
}

Definition

Linear search is a method of finding a value in an array by checking each element in sequence, starting from the first and moving to the last, until the value is found or the end is reached.

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Sezione 2. Capitolo 1

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Suggested prompts:

Can you show me an example of how to search for a value in an array?

What is the most efficient way to search for a value in a large array?

How do I handle searching for values that might appear multiple times in an array?

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Program.cs


              1234567891011121314151617181920212223242526272829
            
using System;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main()
        {
            int[] numbers = { 10, 25, 30, 47, 58 };
            int target = 30;
            int foundIndex = -1;

            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i] == target)
                {
                    foundIndex = i;
                    break;
                }
            }

            if (foundIndex != -1)
            {
                Console.WriteLine("Number " + target + " found at index " + foundIndex + ".");
            }
        }
    }
}

Program.cs


              123456789101112131415161718192021222324252627282930313233
            
using System;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main()
        {
            int[] numbers = { 11, 22, 33, 44, 55 };
            int target = 99;
            int foundIndex = -1;

            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i] == target)
                {
                    foundIndex = i;
                    break;
                }
            }

            if (foundIndex != -1)
            {
                Console.WriteLine("Number " + target + " found at index " + foundIndex + ".");
            }
            else
            {
                Console.WriteLine("Number " + target + " not found in the array.");
            }
        }
    }
}

Definition

Linear search is a method of finding a value in an array by checking each element in sequence, starting from the first and moving to the last, until the value is found or the end is reached.

Tutto è chiaro?

Grazie per i tuoi commenti!

Sezione 2. Capitolo 1

Searching for Elements

1. What is the time complexity of a linear search in an array?

2. How can you determine if a value exists in an array?

3. What should your program do if the searched value is not found?

Searching for Elements

1. What is the time complexity of a linear search in an array?

2. How can you determine if a value exists in an array?

3. What should your program do if the searched value is not found?