QuickBlog – Finding a value in a PowerShell Hash table – Simple!!

For this quick blog, let’s create a month hash object table containing the number and name of the month.  Then, we are going to query this Hash Table object for a specific month.

1. Creating our Month Hash Table:

$MonthHashTable = @{ `
[int] "1" = "January"; `
[int] "2" = "February"; `
[int] "3" = "March"; `
[int] "4" = "April"; `
[int] "5" = "May"; `
[int] "6" = "June"; `
[int] "7" = "July"; `
[int] "8" = "August"; `
[int] "9" = "September"; `
"10" = "October"; `
"11" = "November"; `
"12" = "December"; `
};

Notice in this example, we’ve assigned ‘Strong-typed’ values to most of the keys (month number) as Integer, and leaving the last three to default to a string data “data type“.

Keep in mind, in a Hash Table you have Keys, and Values.  So, we are going to search for a ‘Key’ in order to get the ‘Value’ so we can extract the Month name.

Here’s the Hash Table Syntax for finding the value using the key:
$yourHashTable.Item( [#key#] )

2. Lets go and Looking for the fourth and eleventh month name:

## ----------------------------------------
## - Getting "April":
## - Value stored as Integer for "April":
$mth = 4;

## - Bad, passing a string value when expecting an Integer
## -> no key found, nothing to return:
$MonthHashTable.Item("4");

## - Good, getting month name using Integer value
## -> keys found, a values are returned:
$MonthHashTable.Item(4);
April

$MonthHashTable.Item($mth);
April

## ----------------------------------------
## - Getting "November":
## - Value stored as Integer for "November":
$mth = 11;

## - Bad, passing an integer value when expecting a string
## -> no key found, nothing to return:
$MonthHashTable.Item(11);

## - Bad, passing an integer value when expecting a string
## -> no key found, nothing to return:
$MonthHashTable.Item($mth);

## - Value stored as String for "November":
$mth = "11";

## - Good, getting month name using String value:
## -> key found, a value is returned:
$MonthHashTable.Item($mth);
November

As the sample show, we need to make sure the variable value must have the proper “data type” so it can find the key.

Happy PowerShelling!!