Windows

Problem

You want to use PowerShell to calculate simple mathematical results.

Solution

Use PowerShell’s arithmetic operators:

+
Addition

-
Subtraction

*
Multiplication

/
Division

%
Modulus

+=, -=, *=, /=, and %= Assignment variations of the above ( ) Precedence/Order of operations

Discussion

One of the strongest features of PowerShell is its objectbased pipeline. You don’t waste your energy creating, destroying, and recreating the object representation of your data. In other shells, you lose the fullfidelity representation of data when the pipeline converts it to pure text. You can regain some of it through excessive text parsing, but not all of it.

However, you still often have to interact with lowfidelity input that originates from outside PowerShell. Textbased data files and legacy programs are two examples.

Problem

You want to control the way that PowerShell displays or formats a date.

Solution

To control the format of a date, use one of the following options:

• The GetDate cmdlet’s –Format parameter:

PS >GetDate Date "05/09/1998 1:23 PM" Format "ddMMyyyy @ hh:mm:ss" 09051998 @ 01:23:00

• PowerShell’s string formatting (f) operator:

PS >$date = [DateTime] "05/09/1998 1:23 PM" PS >"{0:ddMMyyyy @ hh:mm:ss}" f $date 09051998 @ 01:23:00

• The object’s ToString() method:

Problem

You want to remove leading or trailing spaces from a string or user input.

Solution

Use the Trim() method of the string to remove all leading and trailing whitespace characters from that string.

PS >$text = " `t Test String`t `t" PS >"|" + $text.Trim() + "|" |Test String|

Discussion

Problem

You want to convert a string to uppercase or lowercase.

Solution

Use the ToUpper() and ToLower() methods of the string to convert it to uppercase and lowercase, respectively. To convert a string to uppercase, use the ToUpper() method:

PS >"Hello World".ToUpper()

HELLO WORLD To convert a string to lowercase, use the ToLower() method:

PS >"Hello World".ToLower()

hello world

Discussion

Problem

You want to replace a portion of a string with another string.

Solution

PowerShell provides several options to help you replace text in a string with other text.

Use the Replace() method on the string itself to perform simple replacements:

PS >"Hello World".Replace("World", "PowerShell")

Hello PowerShell Use PowerShell’s regular expression –replace operator to perform more advanced regular expression replacements:

PS >"Hello World" replace '(.*) (.*)','$2 $1' World Hello

Discussion

Problem

You want to determine if a string contains another string, or want to find the position of a string within another string.

Solution

PowerShell provides several options to help you search a string for text.

Use the –like operator to determine whether a string matches a given DOSlike wildcard:

PS >"Hello World" –like "*llo W*"

True Use the –match operator to determine whether a string matches a given regular expression:

PS >"Hello World" –match '.*l[lz]o W.*$' True

Problem

You want to place formatted information (such as rightaligned text or numbers rounded to a specific number of decimal places) in a string.

Solution

Use PowerShell’s formatting operator to place formatted information inside a string.

PS >$formatString = "{0,8:D4} {1:C}`n" PS >$report = "Quantity Price`n" PS >$report += "`n" PS >$report += $formatString f 50,2.5677 PS >$report += $formatString f 3,9 PS >$report Quantity Price

0050 $2.57 0003 $9.00

Discussion

Problem

You want to prevent PowerShell from interpreting special characters or variable names inside a string.

Solution

Use a nonexpanding string to have PowerShell interpret your string exactly as entered. A nonexpanding uses the single quote character around its text.

PS >$myString = 'Useful PowerShell characters include: $, `, " and { }' PS >$myString Useful PowerShell characters include: $, `, " and { }

If you want to include newline characters as well, use a nonexpanding here string, as in Example 52.