String Concatenation Operation

VBScript Tutorials - Herong's Tutorial Examples - Version 5.20, by Dr. Herong Yang

VBScript Tutorials - Herong's Tutorial Examples

∟String Operations - Concatenation and Comparison

∟String Concatenation Operation

This section provides a quick introduction of string concatenation operation, which joins the second string to the end of the first string.

String concatenation operation is an operation that:

Operates on two operands of String values using (&) as the operator.
Produces a new string by concatenating the second operand to the end of the first operand.
Returns a String value.
If an operand is not a String value, it will be converted to a String value.
If both operands are String values, the add operator (+) can also be used as the concatenation operator.

Here is a tutorial example showing you how string concatenation operation works:

<html>
<body>
<!-- string_concatenation.html
 - Copyright (c) 2015, HerongYang.com, All Rights Reserved.
-->
<pre>
<script language="vbscript">
   document.writeln("Hello " & "world!")
   document.writeln("649 = " & 649)
   document.writeln("True = " & True)
   document.writeln("#31-Dec-1999# = " & #31-Dec-1999#)
   document.writeln("Empty = " & Empty)
   document.writeln("Null = " & Null)
   document.writeln("Hello " + "world!")
   document.writeln("649 " + 649)
'   document.writeln("Game " + 649)
</script>
</pre>
</body>
</html>

Here is the output of this VBScript example script:

Hello world!
649 = 649
True = True
#31-Dec-1999# = 12/31/1999
Empty = 
Null = 
Hello world!
1298

The output confirms some of string concatenation operation rules:

("649 = " & 649) was executed as a string concatenation operation. The second operand 649 was converted from an Integer value to a String value "649" before the operation.
("True = " & True) was executed as a string concatenation operation. The second operand True was converted from a Boolean value to a String value "True" before the operation.
("#31-Dec-1999# = " & #31-Dec-1999#) was executed as a string concatenation operation. The second operand #31-Dec-1999# was converted from a Date value to a String value "31-Dec-1999" before the operation.
("Empty = " & Empty) was executed as a string concatenation operation. The second operand Empty was converted from an Empty value to a String value "" before the operation.
("Null = " & Null) was executed as a string concatenation operation. The second operand Null was converted from a Null value to a String value "" before the operation.
("Hello " + "world!") was executed as a string concatenation operation. The add operator (+) works as a string concatenation operator if both operands are String values.
("649 " + 649) was executed as an arithmetic addition operation. If one operand is a numeric value, the add operator (+) works as an arithmetic addition operator.
("Game " + 649) was an invalid operation. The first operand "Game " could not be converted into a numeric value.