word frequency counter program in c code example

Example: word frequency analysis c program

#include <stdbool.h>#include <stdio.h>#include <glib.h> typedef struct word_count_tag {    const char* word;    size_t count;} word_count; int compare_word_count(const void* p1, const void* p2) {    const word_count* w1 = p1;    const word_count* w2 = p2;    if (w1->count > w2->count)        return -1;    if (w1->count < w2->count)        return 1;    return 0;} bool get_top_words(const char* filename, size_t count) {    GError* error = NULL;    GMappedFile* mapped_file = g_mapped_file_new(filename, FALSE, &error);    if (mapped_file == NULL) {        fprintf(stderr, "%s\n", error->message);        g_error_free(error);        return false;    }    const char* text = g_mapped_file_get_contents(mapped_file);    if (text == NULL) {        fprintf(stderr, "File %s is empty\n", filename);        g_mapped_file_unref(mapped_file);        return false;    }    gsize file_size = g_mapped_file_get_length(mapped_file);    // Store word counts in a hash table    GHashTable* ht = g_hash_table_new_full(g_str_hash, g_str_equal,                                           g_free, g_free);    GRegex* regex = g_regex_new("\\w+", 0, 0, NULL);    GMatchInfo* match_info;    g_regex_match_full(regex, text, file_size, 0, 0, &match_info, NULL);    while (g_match_info_matches(match_info)) {        char* word = g_match_info_fetch(match_info, 0);        char* lower = g_utf8_strdown(word, -1);        g_free(word);        size_t* count = g_hash_table_lookup(ht, lower);        if (count != NULL) {            ++*count;            g_free(lower);        } else {            count = g_new(size_t, 1);            *count = 1;            g_hash_table_insert(ht, lower, count);        }        g_match_info_next(match_info, NULL);    }    g_match_info_free(match_info);    g_regex_unref(regex);    g_mapped_file_unref(mapped_file);     // Sort words in decreasing order of frequency    size_t size = g_hash_table_size(ht);    word_count* words = g_new(word_count, size);    GHashTableIter iter;    gpointer key, value;    g_hash_table_iter_init(&iter, ht);    for (size_t i = 0; g_hash_table_iter_next(&iter, &key, &value); ++i) {        words[i].word = key;        words[i].count = *(size_t*)value;    }    qsort(words, size, sizeof(word_count), compare_word_count);     // Print the most common words    if (count > size)        count = size;    printf("Top %lu words\n", count);    printf("Rank\tCount\tWord\n");    for (size_t i = 0; i < count; ++i)        printf("%lu\t%lu\t%s\n", i + 1, words[i].count, words[i].word);    g_free(words);    g_hash_table_destroy(ht);    return true;} int main(int argc, char** argv) {    if (argc != 2) {        fprintf(stderr, "usage: %s file\n", argv[0]);        return EXIT_FAILURE;    }    if (!get_top_words(argv[1], 10))        return EXIT_FAILURE;    return EXIT_SUCCESS;}