Tutorial by Topics: hash



A Hash is a dictionary-like collection of unique keys and their values. Also called associative arrays, they are similar to Arrays, but where an Array uses integers as its index, a Hash allows you to use any object type. You retrieve or create a new entry in a Hash by referring to its key.

As more secure web services avoid storing passwords in plain text format, languages such as PHP provide various (undecryptable) hash functions to support the more secure industry standard. This topic provides documentation for proper hashing with PHP.

A Hash Table is a structure which maps keys to values. See Hash Table for details.

There is a built in easy way to read files in binary within VBA, however it has a restriction of 2GB (2,147,483,647 bytes - max of Long data type). As technology evolves, this 2GB limit is easily breached. e.g. an ISO image of Operating System install DVD disc. Microsoft does provide a way to overcome this via low level Windows API and here is a backup of it.

Also demonstrate (Read part) for calculating File Hashes without external program like fciv.exe from Microsoft.

hashlib implements a common interface to many different secure hash and message digest algorithms. Included are the FIPS secure hash algorithms SHA1, SHA224, SHA256, SHA384, and SHA512.

Hashtable is a class in Java collections which implements Map interface and extends the Dictionary Class

Contains only unique elements and its synchronized

Concepts of weak Hashmap

LinkedHashMap class is Hash table and Linked list implementation of the Map interface, with predictable iteration order. It inherits HashMap class and implements the Map interface.

The important points about Java LinkedHashMap class are: A LinkedHashMap contains values based on the key. It contains only unique elements. It may have one null key and multiple null values. It is same as HashMap instead maintains insertion order.


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