lrucache

A simple C++ implementation for a Least Recently Used (LRU) Cache.

Compiling and running

If you are on a Linux distribution:

1. Open a terminal at the directory where the project's sources have been downloaded
2. In the project's root directory , execute the following commands (make sure you have g++ compiler installed in your environment):

  g++ -o main main.cpp
  ./main

The source code file main.cpp will be compiled producing the executable main, which runs immediately afterwards.

If you are on a Windows system:

1. Open a command prompt window at the directory where the project's sources have been downloaded
2. Make sure you meet all prerequisites for compiling native C++ program in your environment with cl.exe compiler (please, refer to this link for further details).
3. If everything is fine, in the project's root directory , execute the following command:

  cl /EHsc main.cpp

The cl.exe compiler generates an .obj file that contains the compiled code, and then runs the linker to create an executable proram named main.exe. To run this program at the command prompt, just type the following line in the shell:

  main

The program will be executed and its output will be shown on the prompt window.

Instead of using the shell terminal or command prompt, you may also consider install an IDE to aid in compiling and running the C++ source code, such as Dev-C++, Code::Blocks, CLion, VisualStudio, XCode, Eclipse, NetBeans, Qt Creator, among others.

Playing with the code

The executable program will run all instructions declared inside the function main() of the source code file main.cpp, including:

const unsigned N = 4;

// Instantiates a LRUCache object  
LRUCache lruCache;

// Initializes the cache with capacity for N entries
lruCache.build(N);

// Adds some data into cache
lruCache.add(0, "Marvin");
lruCache.add(1, "Ford Prefect");
lruCache.add(0, "Another Marvin");
lruCache.add(13,"Lisbeth Salander");
lruCache.add(3, "Mikael Blomkvist");
lruCache.add(4, "Alicia Florrick");
lruCache.add(1, "Kalinda Sharma");
lruCache.add(5, "Don't panic!");

// Reads data from cache given certain (existing or non-existing) keys
try {
  cout << "Value '" << lruCache.get(3) << "' read." << endl;
  cout << "Value '" << lruCache.get(11) << "' read." << endl;
} catch (const std::invalid_argument &e) {
  cerr << "An error has occurred while reading data from cache: " << e.what() << endl;
}

// Purges all cache's content along with any other data related to it
lruCache.destruct();

In order to test different behaviors, just update the function main()'s content, by changing the cache's capacity (expressed in the constant N) and rebuilding it with operation build(unsigned n); or even by inserting and reading data in cache with distinct keys using the operations add(unsigned key, string data) and get(unsigned key). You may also use the operation destruct() to clear all cache data.

Once you have changed the function main() with new contents, do not forget to recompile your code before running it to see the new results.