Small anagram finder in c++. Generates a hash table from a dictionary file of words.

anagram_finder.cpp

/**
 * \author Lars Gröber
 */

#include <iostream>
#include <fstream>
#include <vector>
#include <unordered_map>
#include <thread>
#include <map>
#include <sstream>
#include <algorithm>
#include <numeric>

std::string hash_word ( const std::string& s )
{
    std::string hash = "00000000000000000000000000";
    for ( char c : s )
    {
        if ( isalpha( c ) )
        {
            hash[c - 'a']++;
        }
    }
    return hash;
}

void print_vector ( const std::vector<std::string>& v, const std::string& original = "" )
{
    for ( const auto& s : v )
    {
        if ( s != original )
        {
            std::cout << s << " ";
        }
    }
    std::cout << std::endl;
}

int main ( int argc, char const* argv[] )
{
    if ( argc != 2 )
    {
        std::cout << "Usage: " << argv[0] << " dic_file\n";
        return 0;
    }

    std::string file_name = argv[1];


    std::ifstream file( file_name );

    if ( !file.is_open() )
    {
        std::cout << "Opening file failed!" << '\n';
        return -1;
    }

    std::unordered_map<std::string, std::vector<std::string>> hash_table;

    std::cout << "Generating hash table..." << std::flush;

    for ( std::string line; std::getline( file, line ); )
    {
        if (line[line.length() - 1] == '\r')
        {
            line = line.substr( 0, line.length() - 1 );
        }

        std::transform( line.begin(), line.end(), line.begin(), ::tolower );
        (hash_table[hash_word( line )]).push_back( line );
    }

    std::cout << "Done\n";
    std::cout << "Found " << std::accumulate( hash_table.begin(), hash_table.end(), 0, [] ( int a, auto b )
    {
        return (b.second.size() > 1) ? a + 1 : a;
    } ) << " anagrams\n\n";
    std::cout << "Write '\\exit' to exit.\n";

    while ( true )
    {
        std::cout << "Please give a word:\n";
        std::string input;
        std::getline( std::cin, input );

        if ( input == "\\exit" )
        { break; }

        std::transform( input.begin(), input.end(), input.begin(), ::tolower );
        print_vector( hash_table[hash_word( input )], input );
    }

    return 0;
}