How to set a null value to a value type?



A value type, by definition, can not be null : it necessarily a value.

However, there is a generic type Nullable which allows to include a value type, and can assert null :

?View Code CSHARP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

 
        //  integer  not  nullable 
	int monInt1 =  42 ;
 
	//  integer  nullable 
	nullable < int > monInt2 =  null ;
 
	//  integer  nullable,  scoring  short 
	int? monInt3 =  null ;
 
	//  Conversion  implicit  in  int  to  nullable <int> 
	monInt2 = monInt1 ;
 
	// Copy of an int to a Nullable <int>
	if (monInt2.HasValue)
	{
		// No implicit conversion from int to nullable <int>, use the Value property
		monInt1 = monInt2.Value;
	}

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-set-a-null-value-to-a-value-type/

2011-12-05 by liuyunsx | Categories : C# | Tags: c#, dotnet, null, type | No Comments

How to calculate the time interval between two dates?



The difference between two dates is done using the operator – which is redefined in the DateTime type to return an object of type TimeSpan (time interval).
calculate the number of days since the creation of this issue :

?View Code CSHARP
1
2
3
4
5

      DateTime DateCourante = DateTime.Now;
      DateTime DateCreationquestion = new DateTime(2007, 1, 3);
 
      TimeSpan Ts = DateCourante - DateCreationquestion;
      Console.WriteLine("It took {0} day (s) since the inception of this question!", Ts.Days);

Note that various arithmetic operators are redefined in the DateTime and TimeSpan structures, so that it can perform various operations on dates.

DateTime – DateTime = TimeSpan
DateTime + TimeSpan = DateTime
DateTime – TimeSpan = DateTime
TimeSpan + TimeSpan = TimeSpan
DateTime + DateTime = impossible because it does not make sense

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-calculate-the-time-interval-between-two-dates/

2011-12-05 by liuyunsx | Categories : C# | Tags: c#, date, dotnet, TimeSpan | No Comments

How to retrieve the default of a kind?



The keyword default provides the default of a type. For a reference type, the default value is always null .

For a value type, default value is an instance of the type where all fields have their default value (all bytes to 0).

?Download download.txt
1
2

Console.WriteLine("Default value of int : {0}", default(int) != null ? default(int).ToString() : "NULL");
      Console.WriteLine("Default string : {0}", default(string) != null ? default(string).ToString() : "NULL");

This keyword is especially useful when writing a generic class or method.

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-retrieve-the-default-of-a-kind/

2011-12-04 by liuyunsx | Categories : C# | Tags: c#, dotnet, type | No Comments

How to perform a bit shift on a number?



You can perform a shift left or right of a number of bits using the operators “and”:

?View Code CSHARP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

      int value =  8 ; 
      int res ;
 
      Console . WriteLine ( " The  value  of  start  is  {0} " , value) ;
 
      // Shift Left
      // res is multiplied by 2
      res = value << 1;
      Console.WriteLine("After a lag of one to the left, is res {0}", res);
 
      // Shift Right
      // res is divided by 2
      res = value >> 1;
      Console.WriteLine("After a lag of one to the right, is res {0}", res);
 
      // Shift Left
      // res is multiplied by 4
      res = value << 2;
      Console.WriteLine("After a lag of two to the left, is res {0}", res);

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-perform-a-bit-shift-on-a-number/

2011-12-04 by liuyunsx | Categories : C# | Tags: c#, dotnet, number | No Comments

How to declare and use the one-dimensional arrays?



To use an array, C #, you must follow the type of the array elements by [].

To access the array elements, you must navigate by using the index (attention, the first index of array elements starts at 0 and not 1)

?View Code CSHARP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

public class Tableau
    {
        // An array of type string
        private string[] _TableauString;
 
        public static void Main()
        {
            // We define the array size
            _TableauString = new string[3];
 
            // Fill the table
            for (int i = 0; i < 3; i++)
            {
                _TableauString[i] = "Chaine " + i;
            }
 
            // Viewing the contents of the table
            for (int i = 0; i < 3; i++)
            {
                Console.Write("Case " + i);
                Console.WriteLine("Contenu: " + _TableauString[i]);
            }
        }
    }

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-declare-and-use-the-one-dimensional-arrays/

2011-11-12 by liuyunsx | Categories : C# | Tags: arrays, c#, dotnet | No Comments

How to verify that an object is of a certain type?



There are two solutions to determine if an object is of a type:

The first is to use the keyword is. It returns true if the object is of the type requested:

?View Code CSHARP
1
2
3
4
5

String monString = "This is a test!";
      if (monString is String)
          Console.WriteLine("monString is String!");
      else
          Console.WriteLine("monString is not a String!");

Read more »

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-verify-that-an-object-is-of-a-certain-type/

2011-10-19 by liuyunsx | Categories : C# | Tags: . NET Framework, c#, dotnet, verify object, verify type | No Comments

How to use a reserved keyword as a variable name or function?



While this is not recommended, it is possible to use a reserved keyword by prefixing the “@” character.

?View Code CSHARP
1
2
3
4

void @while()
      {
          int @class = 2007;
      }

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-use-a-reserved-keyword-as-a-variable-name-or-function/

2011-10-19 by liuyunsx | Categories : C# | Tags: . NET Framework, dotnet, keyword | No Comments

How to refer to the current object?



In C #, it is possible to explicitly access to members of the current object via the this keyword.

This allows an ambiguity if a local variable or parameter has the same name as a member of the current object:

?View Code CSHARP
1
2
3
4
5
6
7
8
9

class ExempleThis
{
private String monString;
 
public ExempleThis(string monString)
{
this.monString = monString;
}
}

The keyword this can also refer to the current object, for example to pass it to another class:

?View Code CSHARP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

class Parent
	{
	    private List<Enfants> _enfants = new List<Enfant>();
 
		public IEnumerable<Enfant> Enfants
		{
			get { return _enfants; }
		}
 
		public Enfant AddEnfant()
		{
			Enfant e = new Enfant(this); // On passe l'objet courant en paramètre
			_enfants.Add(e);
			return e;
		}
	}
 
	class Enfant
	{
	    public Enfant(Parent parent)
	    {
	    	this.Parent = parent;
	    }
 
	    public Parent Parent { get; private set; }
	}

Please indicate the source reference, the original address:
 www.mydeveloperblog.com/dotnet/c-sharp/how-to-refer-to-the-current-object/

2011-10-04 by liuyunsx | Categories : C# | Tags: . NET Framework, c#, dotnet, refer | No Comments

Page 1 of 3312345«102030...Last »
Related searches:
dotnet datetime default string object
gipoco.com is neither affiliated with the authors of this page nor responsible for its contents. This is a safe-cache copy of the original web site.