Validate Data Models Using DataAnnotations Attributes C#

C# > System > ComponentModel > DataAnnotations

Provides attribute classes that are used to define metadata.

Example

Validate property class with range numbers

using System;

using System.ComponentModel.DataAnnotations;

using System.Windows.Forms;

namespace WindowsFormsApplication8

{

    public class Person

    {

        private int id;

        [Display(Name = "Person Id")]

        [Range(0, 1000)]

        public int Id

        {

            get { return id; }

            set

            {

                Validator.ValidateProperty(value,

                    new ValidationContext(this, null, null) { MemberName = "Id" });

                id = value;

            }

        }

    }

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            Person p = new Person();

            p.Id = 1;

            p.Id = 1001;

        }

    }

}

Rename files from a folder C#

C# > Files > File Class > Move

Moves a specified file to a new location.

• option to specify a new file name

Example 

Rename files from a folder 

DirectoryInfo d = new DirectoryInfo(@"D:\folder");

FileInfo[] infos = d.GetFiles("*.*");

int i = 1;

foreach (FileInfo f in infos)

{

  File.Move(f.FullName, Path.Combine(f.DirectoryName, + i.ToString() + ".jpg"));

  i++;

}

Mock Assembly Unit Test C#

C# > Unit tests > Mock Assembly 

If you try to mock

var mock = new Mock<Assembly>();

You will get this error:

The type System.Reflection.Assembly implements ISerializable, but failed to provide a deserialization constructor

Solution

Mock _Assembly interface instead of Assembly class.

var mock = new Mock<_Assembly>();

mock.Setup(w => w.GetTypes()).Throws(new Exception());

yield C# Example with KeyValuePair

C# > Keywords > yield

Yield  returns each element one at a time.

When to use:

• when calculate the next item in the list 
• for infinite sets

Example

IEnumerable<KeyValuePair<string, string>> dataList = GetData();

dataList.ToList().ForEach(s => MessageBox.Show(s.Key + s.Value));

private IEnumerable<KeyValuePair<string, string>> GetData()

{

yield return new KeyValuePair<string, string>("1", "A");

yield return new KeyValuePair<string, string>("2", "B");

yield return new KeyValuePair<string, string>("3", "C");

}

Concatenate list of strings c#

C#>  Enumerable > Aggregate

Aggregate performs a calculation over a sequence of values.

Example

List<string> items = new List<string>() { "1", "2", "3", "4" };

var x = items.Aggregate((a, b) => a + "," + b); // "1,2,3,4"

XmlNamespaceManager class c#

C# > XML > XmlNamespaceManager

XML namespaces associate element and attribute names in an XML document with custom and predefined URIs.

Methods

• AddNamespace

Convert ushort to byte array and to ASCII code C# using BitConverter

C#  > System > BitConverter

Converts 

• base data types to an array of bytes,
• array of bytes to base data types.

Example

Convert ushort to ASCII code.
(ascii code 2 bytes array)

ushort number = 5678;

byte[] byteArray = BitConverter.GetBytes(number);

foreach (var result in byteArray)

{

string val = System.Convert.ToChar(result).ToString();

}

How To Convert A Number To an ASCII Character C#

C#  > System > Convert > ToChar

Converts the value of the specified 8-bit unsigned integer to its equivalent Unicode character.

Example

Convert a number to an ASCII Character

 var asciiCode = System.Convert.ToChar(65).ToString(); // 'A'

Convert Class C#

C#  > System > Convert Class

This class is used for conversion to and from the base data types in the .NET Framework.

Methods

• ToChar

Get all IP Addresses from devices attached to the machine C#

C# > System.Net > Dns > IPHostEntry > AddressList

AddressList gets or sets a list of IP addresses that are associated with a host.

Example

Get all IP Addresses from devices attached to the machine 

string hostName = Dns.GetHostName();

IPHostEntry ipHostEntry = Dns.GetHostEntry(hostName);

foreach (IPAddress item in ipHostEntry.AddressList)

{

var IPAddress = item.ToString();

…

}

C# Unit test to check if the class implements an interface with IsInstanceOfType method

C# > Assert Class > IsInstanceOfType

This method verifies that the specified object is an instance of the specified type. 

Example

Test class implements a specific interface.

var result = typeof(MyClass).GetInterfaces()[0];

// Assert

Assert.IsInstanceOfType(typeof(IMyClass), result.GetType());