Get and set accessors in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a get accessor in C# properties?

The get accessor is used to read or retrieve the value of a property. It allows external code to access the property's value safely.

beginner

What does the set accessor do in a C# property?

The set accessor allows you to assign or change the value of a property. It usually takes an implicit parameter called value representing the new value.

intermediate

Explain how to create a read-only property using get and set accessors.

To create a read-only property, define only the get accessor without a set. This means the property value can be read but not changed from outside the class.

beginner

What is the implicit parameter inside a set accessor called, and what is its role?

The implicit parameter inside a set accessor is called value. It holds the value that is being assigned to the property.

beginner

Show a simple example of a C# property with both get and set accessors.

Example:

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

This property allows reading and writing the age field.

What happens if you omit the set accessor in a property?

A The property cannot be accessed at all.

B The property becomes read-only.

C The property becomes write-only.

D The property throws an error.

Without a set, the property can only be read, making it read-only.

Inside a set accessor, what keyword represents the value being assigned?

A this

B newValue

C set

D value

The keyword value holds the new value assigned to the property.

Which accessor is required to read a property value?

A init

B set

C get

D delete

The get accessor allows reading the property's value.

How do you make a property write-only?

A Include only the <code>set</code> accessor.

B Include only the <code>get</code> accessor.

C Include both <code>get</code> and <code>set</code> accessors.

D Use a private field without accessors.

A property with only a set accessor can be assigned but not read.

What is the default accessibility of get and set accessors if not specified?

A They inherit the property's accessibility.

B They are always public.

C They are always private.

D They cause a compilation error.

Accessors inherit the accessibility level of the property unless explicitly changed.

Describe how get and set accessors work together in a C# property.

Think about how you read and write values safely.

Explain how to create a read-only property and why you might want to do that.

Consider when you want to share data but keep it safe.

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