PowerShell for Microsoft SharePoint 2010 : Arithmetic Operators

The basic arithmetic operators include those to add, multiply, subtract, divide, and calculate the remainder of a division. Table 1 lists these operators.

Let’s take a closer look at the + operator. To add the values 1 and 5 together, you could type this:

PS > 1 + 5
6

To add a string with a numeric value, use this form:

PS > "String" + 5String5

It is also possible to add multiple string values to build up a single string. This example uses the + operator to build up a URL from three strings:

PS > "http://" + "SPServer01" + "/MySite"
http://SPServer01/MySite

You can also add string objects stored in variables together.

PS > $url = "http://SPServer01"
PS > $web = "MySite"
PS > $url + "/" + $web
http://SPServer01/MySite

However, it is not possible to add a string to a numeric value.

PS > 1 + ";#" + "Item"
Cannot convert value "String" to type "System.Int32".
Error: "Input string was not in a correct format."
At line:1 char:4
+ 1 + <<<< "String"
    + CategoryInfo          : NotSpecified: (:) [], RuntimeException
    + FullyQualifiedErrorId : RuntimeException

Windows PowerShell interprets the first argument as an instance of the type System.Int32. When we try to add a System.String value to a System.Int32 value, an error occurs. Windows PowerShell expects an argument of the type System.Int32, and it is not possible to convert a System.String value containing characters other than numeric ones. The following is the correct way to add the values:

PS > "1" + ";#" + "Item"
1;#Item

You can also cast the numeric value using the [string] type literal, which is a PowerShell alias for the System.String type.

PS > [string]1 + ";#" + "Item"
1;#Item

The value on the left side defines the type of the whole operation. You can add a number to a string, since a number can be converted to a string value, as shown in this example:

PS > "#Item" + 1
#Item1

Here are examples of using the other arithmetic operators:

• Use the – operator to subtract numeric values:

         PS > 5 - 4
         1
  

• The - operator also works with negative numbers:

         PS > -1 - 1
         -2
  

• Use the * operator to multiply values:

         PS > 5 * 5
         25
  

• You can also multiply string values with a numeric value:

         PS > "Hello" * 5
         HelloHelloHelloHelloHello
  

• Divide numeric values with the / operator:

         PS > 9 / 3
         3
  

• Use the modulus (%) operator to calculate remainders:

         PS > 10 % 3
         1
         PS > 6 % 2
         0