Get and set accessors in C Sharp (C#)

Introduction

Get and set accessors let you read and change values inside an object safely.

When you want to control how a value is read or changed in a class.

When you want to check or change data before saving it.

When you want to hide the details of how data is stored.

When you want to make some values read-only or write-only.

When you want to add extra actions when a value changes.

Syntax

C Sharp (C#)

public class ClassName
{
    private DataType fieldName;

    public DataType PropertyName
    {
        get { return fieldName; }
        set { fieldName = value; }
    }
}

get returns the value.

set assigns a new value using the keyword value.

Examples

This example shows a simple property Name that gets and sets a private field name.

C Sharp (C#)

public class Person
{
    private string name;

    public string Name
    {
        get { return name; }
        set { name = value; }
    }
}

This example adds a check in set to only allow non-negative ages.

C Sharp (C#)

public class Person
{
    private int age;

    public int Age
    {
        get { return age; }
        set
        {
            if (value >= 0) age = value;
        }
    }
}

This is a short way to create a property without writing a field.

C Sharp (C#)

public class Person
{
    public string Name { get; set; } // Auto-implemented property
}

Sample Program

This program creates a Person object and sets the age. It shows how the set accessor blocks negative values and prints a message.

C Sharp (C#)

using System;

public class Person
{
    private int age;

    public int Age
    {
        get { return age; }
        set
        {
            if (value >= 0) age = value;
            else Console.WriteLine("Age cannot be negative.");
        }
    }
}

class Program
{
    static void Main()
    {
        Person p = new Person();
        p.Age = 25;
        Console.WriteLine($"Age: {p.Age}");

        p.Age = -5; // This should show a warning
        Console.WriteLine($"Age after invalid set: {p.Age}");
    }
}

Important Notes

You can make a property read-only by only providing a get accessor.

Use value inside set to get the new value being assigned.

Auto-implemented properties are quick but you cannot add extra logic inside get or set.

Summary

Get and set accessors let you control how values are read and changed in a class.

You can add checks or extra actions inside get or set.

Auto-properties provide a quick way to create simple properties without extra code.

Practice

1. What is the main purpose of get and set accessors in a C# class?

easy

A. To handle exceptions automatically

B. To define methods that perform calculations

C. To create variables inside a class

D. To control how a property value is read and changed

Solution

1. Step 1: Understand the role of accessors

   Get and set accessors are used to read and write property values in a controlled way.

2. Step 2: Differentiate from other class members

   They are not methods or variables themselves but control access to data.

3. Final Answer:

   To control how a property value is read and changed -> Option D

4. Quick Check:

   Get/set control property access = A [OK]

Hint: Get/set control property reading and writing [OK]

Common Mistakes:

• Confusing accessors with methods
• Thinking they create variables
• Assuming they handle exceptions automatically

2. Which of the following is the correct syntax for an auto-implemented property with get and set accessors in C#?

easy

A. public int Age { get() set(); }

B. public int Age() { get; set; }

C. public int Age { get; set; }

D. public int Age get; set;

Solution

1. Step 1: Identify correct property syntax

   Auto-properties use curly braces with get and set accessors separated by semicolons.

2. Step 2: Check each option

   public int Age { get; set; } matches the correct syntax: public int Age { get; set; }

3. Final Answer:

   public int Age { get; set; } -> Option C

4. Quick Check:

   Auto-property syntax = C [OK]

Hint: Auto-properties use braces with get; set; inside [OK]

Common Mistakes:

• Using parentheses instead of braces
• Missing semicolons after get and set
• Writing get and set without braces

3. What will be the output of the following C# code?

class Person {
  private string name;
  public string Name {
    get { return name; }
    set { name = value.ToUpper(); }
  }
}

var p = new Person();
p.Name = "alice";
Console.WriteLine(p.Name);

medium

A. alice

B. ALICE

C. Name

D. null

Solution

1. Step 1: Analyze the set accessor behavior

   The set accessor converts the assigned value to uppercase before storing it in the private field.

2. Step 2: Analyze the get accessor output

   The get accessor returns the stored uppercase string.

3. Final Answer:

   ALICE -> Option B

4. Quick Check:

   Set converts to uppercase, output = ALICE [OK]

Hint: Set modifies value before storing, get returns stored value [OK]

Common Mistakes:

• Ignoring the ToUpper() call in set
• Assuming original case is preserved
• Confusing field and property names

4. Identify the error in this property definition:

public int Score {
  get { return score; }
  set score = value; }
}

medium

A. Incorrect set accessor syntax

B. Missing semicolon after return statement

C. Missing private field declaration

D. Property name should be lowercase

Solution

1. Step 1: Check set accessor syntax

   The set accessor must use braces { } around its code block, but here it is missing the opening brace.

2. Step 2: Confirm other parts

   The return statement has a semicolon, private field may be declared elsewhere, and property names are PascalCase by convention.

3. Final Answer:

   Incorrect set accessor syntax -> Option A

4. Quick Check:

   Set accessor needs braces = A [OK]

Hint: Set accessor must have braces around code block [OK]

Common Mistakes:

• Omitting braces in set accessor
• Confusing property and field names
• Assuming property names must be lowercase

5. You want to create a property Age that only allows values between 0 and 120. Which implementation correctly enforces this using get and set accessors?

hard

A. private int age; public int Age { get { return age; } set { if (value >= 0 && value <= 120) age = value; } }

B. public int Age { get; set; } // No validation needed

C. private int age; public int Age { get { return age; } set { age = value; } }

D. private int age; public int Age { get { return age; } set { if (value > 0) age = value; } }

Solution

1. Step 1: Check validation logic in set accessor

   private int age; public int Age { get { return age; } set { if (value >= 0 && value <= 120) age = value; } } checks if value is between 0 and 120 before assigning it to the private field.

2. Step 2: Compare other options

   The auto-implemented property has no validation. The simple backing field assignment lacks checks. The partial validation only checks if value > 0, missing the upper limit.

3. Final Answer:

   private int age; public int Age { get { return age; } set { if (value >= 0 && value <= 120) age = value; } } -> Option A

4. Quick Check:

   Set accessor validates range 0-120 = B [OK]

Hint: Use if condition in set to validate value range [OK]

Common Mistakes:

• Not validating upper limit
• Assigning value without checks
• Assuming auto-properties validate automatically