logo Use CA10RAM to get 10%* Discount.
Order Nowlogo
(5/5)

Motivation Hashing Example Interning Subroutines Tips Questions?

INSTRUCTIONS TO CANDIDATES
ANSWER ALL QUESTIONS

1 Lab 5: String Interning

Motivation Hashing Example Interning Subroutines Tips Questions?     

 Suppose we have some text (possibly code) with many long, identical strings:

def long and useless function(long variable name): loop  increment  counter  = 0;

while loop increment counter < long variable name: loop increment counter = loop increment counter + 1 long and useless function(long variable name 1) print(‘‘This isn’t useful!")

During a task such as compiling, we may need to compare these strings (such as variable and function names) many, many times.

This is computationally expensive!

⇒ The solution: string interning.

 Instead of performing comparisons on long strings such as

long and useless function and loop increment counter, we will:

Create a 1 word (4 byte) unique identifier for these strings. Compare these identifiers.

For example:

long and useless function → 0x47fa018b long variable name → 0xcc81b504 loop increment counter → 0x57cf47ab

Now the comparisons can be performed very quickly.

A hashing function takes some data as input and returns a fixed-length representation of that data.

For example:

"123password" d2bc2f8d09990ebe87c809684fd78c66 "This is  a sentence."  d15ba5f31fa7c797c093931328581664 "Hash  me!" e09f9e0c17051e3ad13f4176076cbb92 These are all examples of the MD5 hash algorithm.

There are three things you should note about hash functions:

1 The output is always the same length.

2 Identical input will always produce identical output.

3 If the input is unbounded (can be any length), multiple inputs will have the same output.

 When two different inputs have the same output in a hash function, a collision occurs.

For example:

"Both strings have the same value" 0x5f44a1b3 "for  this  particular  hash  function." 0x5f44a1b3

One of the goals of a hash function is to reduce the number of collisions that occur.

 

(5/5)
Attachments:

Expert's Answer

240 Times Downloaded

Related Questions

. Introgramming & Unix Fall 2018, CRN 44882, Oakland University Homework Assignment 6 - Using Arrays and Functions in C

DescriptionIn this final assignment, the students will demonstrate their ability to apply two ma

. The standard path finding involves finding the (shortest) path from an origin to a destination, typically on a map. This is an

Path finding involves finding a path from A to B. Typically we want the path to have certain properties,such as being the shortest or to avoid going t

. Develop a program to emulate a purchase transaction at a retail store. This program will have two classes, a LineItem class and a Transaction class. The LineItem class will represent an individual

Develop a program to emulate a purchase transaction at a retail store. Thisprogram will have two classes, a LineItem class and a Transaction class. Th

. SeaPort Project series For this set of projects for the course, we wish to simulate some of the aspects of a number of Sea Ports. Here are the classes and their instance variables we wish to define:

1 Project 1 Introduction - the SeaPort Project series For this set of projects for the course, we wish to simulate some of the aspects of a number of

. Project 2 Introduction - the SeaPort Project series For this set of projects for the course, we wish to simulate some of the aspects of a number of Sea Ports. Here are the classes and their instance variables we wish to define:

1 Project 2 Introduction - the SeaPort Project series For this set of projects for the course, we wish to simulate some of the aspects of a number of

240 Times Downloaded

Ask This Question To Be Solved By Our ExpertsGet A+ Grade Solution Guaranteed

expert
Atharva PatilComputer science

503 Answers

Hire Me
expert
Chrisantus MakokhaComputer science

544 Answers

Hire Me
expert
AyooluwaEducation

771 Answers

Hire Me
expert
RIZWANAMathematics

901 Answers

Hire Me

Get Free Quote!

407 Experts Online