Inspecting methods and properties in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of MethodInfo Name Property

What will be the output of this C# code snippet that uses reflection to get method names?

C Sharp (C#)

using System;
using System.Reflection;

class Sample {
    public void Hello() { }
    private int Add(int a, int b) { return a + b; }
}

class Program {
    static void Main() {
        MethodInfo[] methods = typeof(Sample).GetMethods(BindingFlags.Public | BindingFlags.Instance);
        foreach (var method in methods) {
            Console.WriteLine(method.Name);
        }
    }
}

A

Hello
Add

B

Add
Equals
GetHashCode
GetType
ToString

C

Hello
Add
Equals
GetHashCode
GetType
ToString

D

Hello
Equals
GetHashCode
GetType
ToString

💡 Hint

Remember that BindingFlags.Public only includes public methods, so private methods like Add won't appear.

The code uses BindingFlags.Public and Instance to get only public instance methods. 'Hello' is public, 'Add' is private and excluded. The inherited public methods from Object class also appear.

❓ Predict Output

intermediate

PropertyInfo GetValue Output

What will be printed by this C# program that uses reflection to get a property value?

C Sharp (C#)

using System;
using System.Reflection;

class Person {
    public string Name { get; set; } = "Alice";
}

class Program {
    static void Main() {
        Person p = new Person();
        PropertyInfo prop = typeof(Person).GetProperty("Name");
        Console.WriteLine(prop.GetValue(p));
    }
}

A Alice

B Name

C null

D System.String

💡 Hint

GetValue returns the value of the property for the given object instance.

The property 'Name' has the value 'Alice' in the instance p, so GetValue(p) returns 'Alice'.

🔧 Debug

advanced

Why does this reflection code throw an exception?

This code throws a NullReferenceException. What is the cause?

C Sharp (C#)

using System;
using System.Reflection;

class Car {
    private int speed = 100;
}

class Program {
    static void Main() {
        Car c = new Car();
        PropertyInfo prop = typeof(Car).GetProperty("speed");
        Console.WriteLine(prop.GetValue(c));
    }
}

A The class Car does not have any properties, only fields, so GetProperty returns null.

B The field 'speed' is not initialized, causing a null value.

C GetValue requires a static object for private properties.

D The property 'speed' is private and GetProperty without BindingFlags cannot find it, so prop is null.

💡 Hint

Check if 'speed' is a property or a field and how GetProperty works.

GetProperty only finds properties, not fields. 'speed' is a private field, so GetProperty returns null, causing NullReferenceException when calling GetValue.

📝 Syntax

advanced

Which code correctly gets all public properties including inherited ones?

Choose the correct C# code snippet that retrieves all public instance properties of a class including those inherited.

A typeof(MyClass).GetProperties(BindingFlags.NonPublic | BindingFlags.Instance)

B typeof(MyClass).GetProperties(BindingFlags.Public | BindingFlags.Instance)

C typeof(MyClass).GetProperties(BindingFlags.Public | BindingFlags.Static)

D typeof(MyClass).GetProperties(BindingFlags.NonPublic | BindingFlags.Static)

💡 Hint

Public instance properties include those with public getters/setters and are instance members.

BindingFlags.Public | BindingFlags.Instance returns all public instance properties including inherited ones. Other options either get non-public or static properties.

🚀 Application

expert

Count properties with public getter and private setter

Given this class, how many properties have a public getter and a private setter?

C Sharp (C#)

using System;

class Book {
    public string Title { get; private set; }
    public string Author { get; set; }
    public int Pages { get; private set; }
    public DateTime Published { get; private set; }
    private string InternalCode { get; set; }
}

A 1

B 2

C 3

D 4

💡 Hint

Check each property’s getter and setter accessibility carefully.

Title, Pages, and Published have public getters and private setters. Author has public setter, InternalCode is private property.