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Speller

Overview

Speller is a high-performance program that checks the spelling of words in a text file against a dictionary. Built with a hash table for efficient lookups, it identifies misspelled words while providing detailed performance metrics for key operations like loading the dictionary, checking words, and freeing memory.

This project demonstrates core principles of data structures, algorithms, and memory management in C.

Key Features

  • Efficient Spell-Checking: Uses a hash table for rapid word lookups.
  • Customizable Dictionaries: Accepts any dictionary file in plain text format.
  • Performance Metrics: Reports the time taken for:
    • Loading the dictionary.
    • Checking words.
    • Determining dictionary size.
    • Unloading memory.
  • Optimized Hashing: Implements the djb2 hash function for balanced performance and distribution.

Prerequisites

Before running the program, ensure your system has:

  1. A C compiler (clang or gcc).
  2. The make build tool.

Follow the instructions below to install Clang and Make based on your operating system.

Installing Clang and Make

For Ubuntu/Linux

  1. Update your package list: 
    sudo apt update
  2. Install Clang and Make: 
    sudo apt install clang make
  3. Verify Clang installation: 
    clang --version

For macOS

  1. Install Xcode Command Line Tools: 
    xcode-select --install
  2. Verify Clang installation: 
    clang --version

For Windows

  1. Download the LLVM installer from the official LLVM website.
  2. Run the installer and follow the on-screen instructions.
  3. Add the LLVM bin directory (e.g., C:\Program Files\LLVM\bin) to your system's PATH environment variable:
    • Open "Environment Variables" in Windows settings.
    • Edit the Path variable and add the directory.
  4. Verify Clang installation: 
    clang --version

Getting Started

Step 1: Clone the Repository

Clone the project repository to your local machine:

git clone https://github.com/Shahir-47/speller.git
cd speller/speller

Step 2: Compile the Program

Use the provided Makefile to build the program:

make speller

This will generate an executable file named speller.

Step 3: Run the Program

Run the program using the following syntax:

./speller [DICTIONARY] text

Parameters

  • DICTIONARY (optional): Path to the dictionary file. Defaults to dictionaries/large if not provided.
  • text (required): Path to the text file to be spell-checked.

Usage Examples

Using the Default Dictionary

./speller texts/lalaland.txt

Specifying a Custom Dictionary

./speller dictionaries/small texts/shakespeare.txt

Sample Output

MISSPELLED WORDS

[...]
AHHHHHHHHHHHHHHHHHHHHHHHHHHHT
[...]
Shangri
[...]
fianc
[...]

WORDS MISSPELLED:     15
WORDS IN DICTIONARY:  143091
WORDS IN TEXT:        1024
TIME IN load:         0.12
TIME IN check:        0.45
TIME IN size:         0.01
TIME IN unload:       0.04
TIME IN TOTAL:        0.62

Project Structure

├── speller/
│   ├── dictionaries/
│   │   ├── small
│   │   └── large
│   ├── texts/
│   │   ├── (various test text files)
│   ├── dictionary.c
│   ├── dictionary.h
│   ├── speller.c
│   ├── Makefile
└── README.md
  • dictionaries/: Contains dictionary files, including small for debugging and large with 143,091 words.
  • texts/: Test text files for running the program.
  • dictionary.c: Implements dictionary functions like load, check, and unload.
  • dictionary.h: Header file with function prototypes and constants.
  • speller.c: Main program that integrates dictionary functions and benchmarks.
  • Makefile: Automates the build process.

Implementation Details

Key Functions

  • load: Reads the dictionary file into a hash table.
  • check: Checks if a word exists in the hash table.
  • hash: Maps a word to a specific bucket in the hash table.
  • size: Returns the number of words loaded in the dictionary.
  • unload: Frees all memory used by the dictionary.

Hash Table

  • Number of Buckets (N): 24,000 for optimized performance.
  • Hash Function: Based on the djb2 algorithm, designed for speed and uniqueness.

Testing the Program

Predefined Test Files

The texts/ directory contains various test files, such as:

  • lalaland.txt
  • shakespeare.txt
  • tolstoy.txt

Running Tests

To test the program:

./speller dictionaries/small texts/shakespeare.txt

Expected Output

  • A list of misspelled words from the text.
  • Performance benchmarks for dictionary loading, word checking, and unloading.

Authors

Developed by Shahir Ahmed.

License

This project is licensed under the MIT License.