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How to declare and write a script with hash tables on windows and linux
A hash table, also known as a hash map, is a data structure that is used to store key-value pairs. It is an efficient way to store data that can be quickly retrieved using a unique key.
Here is an example of how to declare and write a script with a hash table in Python:
hash_table = {}
hash_table[‘key1’] = ‘value1’
hash_table[‘key2’] = ‘value2’
hash_table[‘key3’] = ‘value3’
print(hash_table[‘key2’]) # Output: “value2”
hash_table[‘key2’] = ‘new value’
print(hash_table[‘key2’]) # Output: “new value”
del hash_table[‘key1’]
print(‘key1’ in hash_table) # Output: False
# Output: False
In this example, we declare an empty hash table using the {} syntax. We then add some key-value pairs to the hash table using the [] syntax. We access a value using its key, modify a value using its key, delete a key-value pair using the del statement, and check if a key is in the hash table using the in operator.
I hope this helps! Let me know if you have any questions.
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Hash tables with powershell on windows
Declaration:
$states=@{“Alberta” = “Calgary”; “British Columbia” = “Vancouver”; “Ontario” = “Toronto” ; “Quebec” = “Montreal”}Name
_____Value
_______Alberta Calgary British Columbia Vancouver Ontario Toronto Quebec Montreal Add new key-value in hashtable:
$states.Add(“Manitoba”,”Winnipeg”)Remove key-value in hashtable:
$states.Remove(“Manitoba”,”Winnipeg”)
Change value in hashtable:
$states.Set_Item(“Ontario”,”Ottawa”)
Retrieve value in hashtable:
$states.Get_Item(“Alberta”)
Find key in hashtable:
$states.ContainsKey(“Alberta”)
Find Value in hashtable:
$states.ContainsValue(“Calgary”)
Count items in hashtable:
$states.Count
Sort items by Name in hashtable:
$states.GetEnumerator() | Sort-Object Name -descending
Sort items by Value in hashtable:
$states.GetEnumerator() | Sort-Object Value -descending -
Hash tables with perl on linux or windows
Declaration:
my %hash = (); #Initialize a hash
my $hash_ref = {}; # Initialize a hash reference. ref will return HASH
Clear (or empty) a hash
for (keys %hash)
{
delete $hash{$_};
}
Clear (or empty) a hash reference
for (keys %$href)
{
delete $href->{$_};
}
Add a key/value pair to a hash
$hash{ ‘key’ } = ‘value’; # hash
$hash{ $key } = $value; # hash, using variables
Using Hash Reference
$href->{ ‘key’ } = ‘value’; # hash ref
$href->{ $key } = $value; # hash ref, using variables
Add several key/value pairs to a hash
%hash = ( ‘key1’, ‘value1’, ‘key2’, ‘value2’, ‘key3’, ‘value3’ );
%hash = (
key1 => ‘value1’,
key2 => ‘value2’,
key3 => ‘value3’,
);Copy a hash
my %hash_copy = %hash; # copy a hash
my $href_copy = $href; # copy a hash ref
Delete a single key/value pair
delete $hash{$key};
delete $hash_ref->{$key};
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Hash tables with python on linux or windows
Hash tables are called dictionary in python.
Declaration:
dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}
Accessing Values
print “dict[‘Name’]: “, dict[‘Name’]
print “dict[‘Age’]: “, dict[‘Age’]
Output:
dict[‘Name’]: Zara
dict[‘Age’]: 7
Updating Dictionary
dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}
dict[‘Age’] = 8; # update existing entry
dict[‘School’] = “DPS School”; # Add new entry
Delete Dictionary Elements
#!/usr/bin/python
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dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’}
del dict[‘Name’]; # remove entry with key ‘Name’
dict.clear(); # remove all entries in dict
del dict ; # delete entire dictionary
