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:

# Declare an empty hash table
hash_table = {}

# Add some key-value pairs to the hash table
hash_table[‘key1’] = ‘value1’
hash_table[‘key2’] = ‘value2’
hash_table[‘key3’] = ‘value3’

# Access a value using its key
print(hash_table[‘key2’]) # Output: “value2”

# Modify a value using its key
hash_table[‘key2’] = ‘new value’
print(hash_table[‘key2’]) # Output: “new value”

# Delete a key-value pair using the `del` statement
del hash_table[‘key1’]

# Check if a key is in the hash table using the `in` operator
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};

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

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

Source:

1. https://technet.microsoft.com/en-us/library/ee692803.aspx
2. http://www.cs.mcgill.ca/~abatko/computers/programming/perl/howto/hash/
3. http://www.tutorialspoint.com/python/python_dictionary.htm