Introduction

The do-while and while statements provide control over code execution flow by repeating a block of code until a condition is satisfied.

Learning Objectives

• Utilize the do-while loop to iterate through a code block.

• Implement the while loop to iterate through a code block as well.

Prerequisites for Developers

• Familiarity with utilizing the if statement.

• Proficiency in using foreach and for iteration statements.

• Competence in writing Boolean expressions.

• Knowledge of generating random numbers using the System.Random class and the Random.Next() method.

Getting Started

What is the do-while loop?

The do-while statement runs a statement or block of statements as long as a specified Boolean expression remains true. As this expression is evaluated after each loop execution, a do-while loop executes at least once.

Example: do-while

Let’s create code that continuously generates random numbers ranging from 1 to 10 until we generate the number 7. The number 7 could be generated in one iteration or after several iterations.

To begin, create a static class file called “WhileLoop.cs” within the console application. Insert the provided code snippet into this file.

/// <summary>
/// Outputs
/// 2
/// 5
/// 8
/// 2
/// 7
/// </summary>
public static void DoWhileLoopExample()
{
    Random random = new Random();
    int current = 0;

    do
    {
        current = random.Next(1, 11);
        Console.WriteLine(current);
    } while (current != 7);
}

Execute the code from the main method as follows

#region Day 5 - While & do-while

WhileLoop.DoWhileLoopExample();

#endregion

Console Output

2
5
8
2
7

Example: while

The while statement will iterate based on the Boolean expression. To do that add another method into the same static class as shown below

/// <summary>
/// Outputs
/// 9
/// 7
/// 5
/// Last number: 1
/// </summary>
public static void WhileLoopExample()
{
    Random random = new Random();
    int current = random.Next(1, 11);

    while (current >= 3)
    {
        Console.WriteLine(current);
        current = random.Next(1, 11);
    }
    Console.WriteLine($"Last number: {current}");
}

Execute the code from the main method as follows

#region Day 5 - While & do-while

WhileLoop.WhileLoopExample();

#endregion

Console Output

9
7
5
Last number: 1

Continue statement with do-while

Sometimes, developers need to skip the rest of the code within a code block and move on to the next iteration. To achieve this add another method into the same static class as shown below

    /// <summary>
    /// Outputs
    /// 5
    /// 1
    /// 6
    /// 7
    /// </summary>
    public static void ContinueDoWhileLoopExample()
    {
        Random random = new Random();
        int current = random.Next(1, 11);

        do
        {
            current = random.Next(1, 11);

            if (current >= 8) continue;

            Console.WriteLine(current);
        } while (current != 7);
    }

Execute the code from the main method as follows

    #region Day 5 - While & do-while

    WhileLoop.ContinueDoWhileLoopExample();

    #endregion

Console Output

    5
    1
    6
    7

Complete Code on GitHub

GitHub — ssukhpinder/30DayChallenge.Net

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