String Concatenation (Cross Ref > Language Details)

C# performs implicit casting of numbers to strings. To concatenate two strings, a string to an integer, or a string to a floating point number, use the + operator. For example, to convert a floating point number to a string just concatenate an empty string to the number as in "" + 3.2.

Alternatively, you can use the System.Text.StringBuilder class which frequently but not always provides faster code.

String FirstName;

String LastName;

Int16 Age;

FirstName = "Mike";

LastName = "Prestwood";

Age = 43;

Console.WriteLine(FirstName + " " + LastName + " is " + Age + ".");

//Implicit casting of numbers.

//

//This fails:

//MessageBox.Show(3.3);

//

//This works:

MessageBox.Show("" + 3.3); 

Although you can use either a & or a + to concatenate values, my preference is to use a + because more languages use it. However, if you use & then some type conversions are done for you. If you use + you will sometimes have to cast a value to concatenate it. For example, you will have to use CStr to cast a number to a string if you use the + operator as a concatenation operator.

Dim FirstName As String
Dim LastName As String
 
FirstName = "Mike"
LastName = "Prestwood"
 
MsgBox "Full name: " & FirstName & " " & LastName

 
MsgBox "2+2=" + CStr(2+2)