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String Concatenation (Cross Ref > Operators)

String Concatenation

Access VBA: "String Concatenation" & or +

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.

Syntax Example:

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

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

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

ASP Classic: "String Concatenation" & or +

Syntax Example:

Dim FirstName
Dim LastName

FirstName  = "Mike"
LastName  = "Prestwood"

Response.Write "Full name: " & FirstName & " " + LastName

Response.Write "2+2=" + CStr(2+2)

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

C#: "String Concatenation" +

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.

Syntax Example:

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);

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

C++: "String Concatenation" + or append

The + operator can be used with any combination of C++ strings, C strings and characters.

Syntax Example:

string fullname;
 
fullname = "Mike ";
fullname.append("Prestwood");
 
cout << "Hello " + fullname + "." << endl;

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

C++/CLI: "String Concatenation" +

C++/CLI 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.

Syntax Example:

//Implicit casting of numbers.

//

//This fails:

//MessageBox::Show(3.3);

//

//This works:

MessageBox::Show("" + 3.3);

Linked Certification Question(s)

The following are practice certification questions with answers highlighted. These questions were prepared by Mike Prestwood and are intended to stress an important aspect of this KB post. All our practice questions are intended to prepare you generally for passing any certification test as well as prepare you for professional work.

Beginner

1 Beginner Level Question

Question #1: True or False?

C++/CLI supports implicit casting which allows you to use the + operator to concatenate strings and numbers as in the following line of code:

MessageBox::Show("I am " + 42 + " years old.");

Answer:

True

False

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Corel Paradox: "String Concatenation" +

String literals s are limited to 255 characters but you can simply add two strings together as in:

s = "A long string." + "Another long string."

Syntax Example:

var
  FirstName  String
  LastName  String
endVar

FirstName  = "Mike"
LastName  = "Prestwood"

msgInfo("", "Full name: " + FirstName + " " + LastName)

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Delphi: "String Concatenation" +

Use the + operator to concatenate two strings. Use IntToStr to convert an integer to a string and FloatToStr to convert a floating point number to a string.

Syntax Example:

var

  FirstName : String;

  LastName : String;

begin

  FirstName := 'Mike';

  LastName := 'Prestwood';

  ShowMessage('Full name: ' + FirstName + ' ' + LastName);

  ShowMessage(FloatToStr(3.2));

end;

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To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Delphi Prism: +

Unlike Delphi, Prism performs implicit casting. 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.

Syntax Example:

var FirstName : String;

var LastName : String;

FirstName := 'Mike';

LastName := 'Prestwood';

ShowMessage('Full name: ' + FirstName + ' ' + LastName);

//Implicit casting of numbers.

//

//This fails:

//MessageBox.Show(3.3);

//

//This works:

MessageBox.Show("" + 3.3);

Delphi Prism String Concatenation (+)

Using System.Text.StringBuilder

Many times using the StringBuilder class is faster than concatenation. If you have extensive string manipulations to perform, consider using the StringBuilder class.

First add System.Text to your uses:

Uses

  System.Text;

Then use the methods from the StringBuilder class. For example, you can use Append and ToString as follows:

method MainForm.StringBuilderBtn_Click(sender: System.Object; e: System.EventArgs);
var
  FirstName : String;
  LastName : String;
  sbFullName := new StringBuilder;
begin
  FirstName := 'Mike';
  LastName := 'Prestwood';


  //Concatenation.
  MessageBox.Show(FirstName + " " + LastName);

  //StringBuilder class.
  sbFullName.Append(FirstName);
  sbFullName.Append(" ");
  sbFullName.Append(LastName);

  MessageBox.Show(sbFullName.ToString);
end;

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Code:

Delphi Prism String Concatenation (+)

Java: "String Concatenation" + or append

In Java, you use either the String concatenation + operator or StringBulder class methods such as append. Since Java compilers frequently create intermediate objects when the + operator is used and don't when StringBuilder.append is used, the append method is faster than the + operator.

In general, use the convenience of a + operator when speed is not an issue. For example, when concatenating a small number of items and when code isn't executed very frequently. A decent rule of thumb is to use the + operator for general purpose programming and then optimize the + operator with StringBuilder.append as needed.

Syntax Example:

Simple + operator example:

System.out.println("Hello" + " " + "Mike.");

Using StringBuilder example:

StringBuilder myMsg = new StringBuilder();

myMsg.append("Hello ");

myMsg.append("Mike.");

 
System.out.println(myMsg);

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

JavaScript: "String Concatenation" +

To concatenate two strings, a string to an integer, or a string to a floating point number, use the + operator. JavaScript performs implicit casting when concatenating a string and a number. For example, to convert a floating point number to a string just concatenate an empty string to the number as in "" + 3.2.

Syntax Example:

 

// -->

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Perl: "String Concatenation" .

Perl uses a period (.) known as a dot to concatenate strings.

Syntax Example:

$fname = "Mike";
$lname = "Prestwood";

$fullname = $fname . $lname . "
";

print "My name is " . "Mike.
";

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

PHP: "String Concatenation" .

PHP uses a period (.) known as a dot to concatenate strings.

Syntax Example:

$fname = "Mike";
$lname = "Prestwood";

$fullname = $fname . $lname . "
";

echo "My name is " . "Mike.
";

PHP String Concatenation (.)

Here's a complete example that demonstrates a few string concepts:

<?PHP
//Now using quotes.
$fname = "Mike";
$lname = "Prestwood";

$fullname = $fname . $lname;

echo $fullname . '<br>';

//Two literals too:
echo "My name is " . "Mike.<br>";

//Long strings.
$MyMsg = "This is a long string and
unlike some other languages. PHP allows
you to put strings on multiple lines 
like this.";

echo $MyMsg;

?>

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

Code:

PHP String Concatenation (.)

VB Classic: "String Concatenation" & or +

Syntax Example:

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

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

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages

VB.Net: "String Concatenation" + or &

To concatenate two strings, use either the + or & operators. The & operator implicitly converts numbers. If you use the + operator to concatenate a string and a number, you have to cast the number as a string with CStr.

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

Syntax Example:

Dim FullName

Dim Age

//You can use + for strings.

FullName = "Prestwood"
Console.WriteLine("Hello " + FullName)

//For implicit casting, use &

Age = 35

Console.WriteLine(FullName & " is " & Age & " years old.")

'Implicit casting of numbers.

'This works:
MessageBox.Show(3.3)

'This fails:

'MessageBox.Show("" + 3.3)

'This works:
MessageBox.Show("" + CStr(3.3))

'Implicit casting &. This also works:

MessageBox.Show("" & 3.3)

More Info

To/From Code Guide: String Concatenation (Cross Ref > Operators) vs. Other Languages