Strings Arrays and Hashtables

Question 1

We create a verbatim string by using…

Answer 1

Double quotes or single quotes.

Question 2

How can we escape a double quote or single quote when creating a verbatim string?

Answer 2

Double up the double quote or single quote. Eg:
“I just wanted to say ““Hello World””, ok?”
‘I can’‘t believe this’

Question 3

What is the escape sequence for strings (e.g. new line etc)

Answer 3

Back tick - `

Question 4

What are the escape sequences for:
Backspace
New Line
Carriage Return
CrLf
Tab

Answer 4

`b (doesn't work in ISE, only regular script window)
`n
`r
`r`n
`t

Question 5

What are Here Strings?

Answer 5

strings that split out over a number of lines:
$heretext = @"
Here 
is 
some
text
"@

Question 6

What are the rules regarding placement of the @” and “@ character sequences with regard to here strings?

Answer 6

@” has to be that the last character sequence at the end of the line (typically just after a variable declaration). The “@ characters have to be at the beginning of a new line.

Question 7

When using here strings, is it necessary to use doubled quotes?

Answer 7

No

Question 8

What is string interpolation?

Answer 8

The ability to dynamically resolve variables within a string. E.g:
$hello = “Hello World”
“This is my greeting: $hello”

Question 9

How can we directly access a collection of items (e.g. Get-ChildItem) ?

Answer 9

Wrap the command in parentheses. E.g.

(Get-ChildItem).Count

Question 10

How do we actually display the name of a variable within a string?

Answer 10

Use backtick: E.g.

$items = (Get-ChildItem).Count
"`$items = $items"

returns “$items = 123”

Question 11

Does string interpolation work with single quotes?

Answer 11

NO!

Question 12

Does string interpolation work with here strings?

Answer 12

Yes :)

Question 13

How do we embed expressions within a string?

Answer 13

Wrap the expression in $(). E.g

“There are $((Get-ChildItem).Count) items in $(Get-Location)”

Question 14

How do we get the current date/time in PS?

Answer 14

Get-Date

Question 15

How can we format strings using C# - esque format?

Answer 15

Use the static Format method of string. E.g.

Question 16

What’s the PS shortcut for [string]::Format()?

Answer 16

Use -f . E.g.
“There are {0} items” -f $itemCount
“There are {0} items in {1}” -f $itemCount, $location

Question 17

Why would you use -f formatting rather than string interpolation?

Answer 17

For formatting, e.g. dates, currencies etc

Question 18

How do you specify number of decimal places for number formatting?

Answer 18

{0:N[# of places]}. E.g.
“{0:N0}” -f 123.34 # returns 123
“{0:N1}” -f 123.34 # returns 123.3
“{0:N2}” -f 123.34 # returns 123.34
“{0:N3}” -f 123.34 # returns 123.340

Question 19

How do we specify the number of right-justified spaces to display a number in?

Answer 19

Use
{0,8:N0} E.g.
“{0,8:N0}” -f 123.34 # Will right align the output with at least 8 characters.

Question 20

How do we format a currency in PS?

Answer 20

{0:C0}
{0:C1}
etc. The output uses the currency symbol for the region that we’re in.

Question 21

How do we format percentages in PS?

Answer 21

{0:P0}
{0:P1}
etc.
e.g. "{0:P0}" -f 0.1234
returns 12%
Note we pass in the fractional part.

Question 22

How do we format hex values in PS?

Answer 22

{0:X0}
e.g.
“{0:X0}” -f 1234
returns 4D2

Question 23

How do we front-pad integers?

Answer 23

{0:D8} -f 123
returns
00000123

Note that “D”ecimal only supports integers.

Question 24

How do we create custom formats in PS?

Answer 24

Use pound sign:
"{0:#,#.###}" -f 123
Gives: 123
"{0:#,#.###}" -f 123.1245
Gives 123.125
Use zeroes after the decimal point to force to that number of places:

“{0:#,#.000}” -f 123.1
gives 123.100

Question 25

How can we use wildcards in PS?

Answer 25

Use -like and:
* = match zero or more characters
? = match exactly a single character
[a-d] The character matches one in the inclusive range

Question 26

How do we perform regex in PS?

Answer 26

use -match then the regex string.

Question 27

How do we define an array in PS?

Answer 27

use comma separated values:

$array = “Blah”, “di”, “Blah”

Question 28

How do we return all values stored in an array?

Answer 28

just use the array variable. E.g.:

$array = "Blah", "di", "Blah"
$array
# returns all values in the array on separate lines.

Question 29

How do we change all the contents of an array?

Answer 29

Just use the initialiser syntax:
$array = 1, 2, 3
$array = “Blah”, “di”

Question 30

What is the formal array creation syntax?

Answer 30

Wrap values in @()

$array = @(1, 2, 3)

Question 31

How do you create an empty array?

Answer 31

Use

$array = @()

Question 32

How can we append an entry to an existing array

Answer 32

Use += syntax:

E.g. $array += 3

Question 33

What is numeric range notation and how can it be used to create and initialise an array?

Answer 33

It's a double dot notation.  E.g.
$array = 1..5
# Loads the array with values 1 through 5 inclusive

Question 34

How can we tell whether a value exists (or not) in an array?

Answer 34

Use -contains and -notcontains  e.g.
$array = 1, 42, 56
$array -contains 42 # returns true
$array -contains 12 # returns false
$array -notcontains 42 # returns false

Question 35

How do we create multi-dimensional arrays?

Answer 35

Create individual arrays and then include those individual arrays in a new array:
$a = 1, 2, 3
$b = 4, 5, 6
$c = $a, $b

Question 36

How do we join all the elements of an array together?

Answer 36

Use -join with the character that you wish to use as the delimiter.
$array -join “, “

Question 37

Hashtables are…

Answer 37

Similar to an array except they use string keys rather than numeric keys

Question 38

How do you declare a hashtable?

Answer 38

Use $v = @{“Key1” = “Value1”; “Key2” = “Value2”}

Question 39

How do you access the value associated with a particular key in a hashtable?

Answer 39

Use either bracket or dot notation:
$h[“KeyName”]
$h.”KeyName”

Question 40

You can use variables as keys in hashtables. How?

Answer 40

$k = "PowerShell"
$hash = @{$k = "Blah"}
$hash.$k
$hash.$($k)
$hash.$("Power" + "Shell")

Question 41

How do you add a new key / value to a hashtable?

Answer 41

$h[“Blah”] = “DiBlah”

Question 42

How do you remove a key / value from a hashtable?

Answer 42

$h.Remove(“Blah”)

Question 43

How do you check if a hashtable contains a particular key?

Answer 43

$h.Contains(“Blah”)

or $h.Keys - contains “Blah”

Question 44

How do you check if a hashtable contains a particular value?

Answer 44

$h.ContainsValue(“Blah”)
or
$h.Values -contains “Blah”

Question 45

How do I get a list of all keys or all values from a hashtable?

Answer 45

$h.Keys
or
$h.Values