feat: Added a program that prints words in alphabetical order using binary tree data structure (#841)

* frequencies of words started

* A program to Print words contained in a file in alphabetical order

* Apply suggestions from code review

Co-authored-by: David Leal <halfpacho@gmail.com>

* appropriate comments added as suggested from code review

* comments cleaned up

* updating DIRECTORY.md

* Apply suggestions from code review

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* commenting re-worded

* Add link to algorithm

* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* main function moved to the bottom and function prototypes deleted

* uint64_t data type used for non negative values

* uint8_t used

* all int types fixed

* detailed explanation of algorithm added

* Update data_structures/binary_trees/words_alphabetical.c

Co-authored-by: David Leal <halfpacho@gmail.com>

* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* tests and documentation added

* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

Co-authored-by: David Leal <halfpacho@gmail.com>

* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* documentation added

* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Update data_structures/binary_trees/words_alphabetical.c

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* Apply suggestions from code review

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* documentation added

* Apply suggestions from code review

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* Add documentation

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@ -38,6 +38,7 @@
* [Red Black Tree](https://github.com/TheAlgorithms/C/blob/master/data_structures/binary_trees/red_black_tree.c)
* [Segment Tree](https://github.com/TheAlgorithms/C/blob/master/data_structures/binary_trees/segment_tree.c)
* [Threaded Binary Trees](https://github.com/TheAlgorithms/C/blob/master/data_structures/binary_trees/threaded_binary_trees.c)
* [Words Alphabetical](https://github.com/TheAlgorithms/C/blob/master/data_structures/binary_trees/words_alphabetical.c)
* Dictionary
* [Dict](https://github.com/TheAlgorithms/C/blob/master/data_structures/dictionary/dict.c)
* [Dict](https://github.com/TheAlgorithms/C/blob/master/data_structures/dictionary/dict.h)

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/**
* @file
* @brief Printing the [words contained in a
* file](http://www.dailyfreecode.com/Code/word-list-reads-text-file-makes-2050.aspx)
* named `file.txt` in alphabetical order and also their frequencies in to
* another file "wordcount.txt"
* @details
* Given a file (`file.txt`) containing words (like a publication or a novel),
* where words are separated by a space, newline, or underscore.
* This program prints (writes or outputs) to another file (`wordcount.txt`),
* the individual words contained in 'file.txt' with their frequencies (number
* of occurences) each on a newline and in alphabetical order. This program uses
* the binary tree data structure to accomplish this task.
* @author [Randy Kwalar](https://github.com/RandyKdev)
*/
#include <assert.h> /// for assert
#include <ctype.h> /// for type checks
#include <inttypes.h> /// for uint64_t based types, int64_t based types
#include <stdbool.h> /// for boolean data type
#include <stdio.h> /// for IO operations
#include <stdlib.h> /// for memory allocation
#include <string.h> /// for string operations
/**
* @brief structure defining a node in the binary tree
*/
struct Node
{
char *word; ///< the word (value) of the node
uint64_t frequency; ///< number of occurences of the word
struct Node *left; ///< pointer to the left child node
struct Node *right; ///< pointer to the right child node
};
/**
* @brief Ends program due to an error
* @param errorMessage the error message to be printed
* @returns void
*/
void endProgramAbruptly(char *errorMessage)
{
fprintf(stderr, "%s\n", errorMessage);
exit(EXIT_FAILURE);
}
/**
* @brief Frees memory when program is terminating
* @param node pointer to current node
* @returns void
*/
void freeTreeMemory(struct Node *node)
{
if (node != NULL)
{
freeTreeMemory(node->left);
freeTreeMemory(node->right);
free(node->word); // freeing node->word because memory was allocated
// using malloc
free(node); // freeing node because memory was allocated using malloc
}
}
/**
* @brief Stores word in memory
* @param word word to be stored in memory
* @returns a pointer to the newly allocated word if the word IS stored successfully
* @returns `NULL` if the word is NOT stored
*/
char *getPointerToWord(char *word)
{
char *string =
(char *)malloc((strlen(word) + 1) * sizeof(char)); ///< pointer to string
// + 1 is for the '\0' character
if (string != NULL)
{
strcpy(string, word);
return string;
}
endProgramAbruptly(
"\nA problem occurred while reserving memory for the word\n");
return NULL;
}
/**
* @brief Closes the file after reading or writing
* @param file pointer to the file to be closed
* @returns void
*/
void closeFile(FILE *file)
{
if (fclose(file)) {
endProgramAbruptly("\nA Problem Occurred while closing a file\n");
}
}
/**
* @brief Reserves memory for new node
* @returns a pointer to the newly allocated node if memory IS successfully reserved
* @returns `NULL` if memory is NOT reserved
*/
struct Node *allocateMemoryForNode()
{
struct Node *node =
(struct Node *)malloc(sizeof(struct Node)); ///< pointer to the node
if (node != NULL)
{
return node;
}
endProgramAbruptly(
"\nA problem occurred while reserving memory for the structure\n");
return NULL;
}
/**
* @brief Writes contents of tree to another file alphabetically
* @param node pointer to current node
* @param file pointer to file
* @returns void
*/
void writeContentOfTreeToFile(struct Node *node, FILE *file)
{
static uint64_t i = 1; ///< for word numbering in the write file
if (node != NULL) // checks if the node is valid
{
writeContentOfTreeToFile(
node->left,
file); // calls `writeContentOfTreeToFile` for left sub tree
fprintf(file, "%-5lu \t %-9lu \t %s \n", i++, node->frequency,
node->word); // prints the word number, word frequency and word
// in tabular format to the file
writeContentOfTreeToFile(
node->right,
file); // calls `writeContentOfTreeToFile` for right sub tree
}
}
/**
* @brief Adds word (node) to the correct position in tree
* @param word word to be inserted in to the tree
* @param currentNode node which is being compared
* @returns a pointer to the root node
*/
struct Node *addWordToTree(char *word, struct Node *currentNode)
{
if (currentNode == NULL) // checks if `currentNode` is `NULL`
{
struct Node *currentNode =
allocateMemoryForNode(); // allocates memory for new node
currentNode->word = getPointerToWord(word); // stores `word` in memory
currentNode->frequency = 1; // initializes the word frequency to 1
currentNode->left = NULL; // sets left node to `NULL`
currentNode->right = NULL; // sets right node to `NULL`
return currentNode; // returns pointer to newly created node
}
int64_t compared = strcmp(word, currentNode->word); ///< holds compare state
if (compared > 0) {
currentNode->right = addWordToTree(word,
currentNode->right); // adds `word` to right sub tree if `word` is
// alphabetically greater than `currentNode->word`
}
else if (compared < 0) {
currentNode->left = addWordToTree(word,
currentNode->left); // adds `word` to left sub tree if `word` is
// alphabetically less than `currentNode->word`
}
else {
currentNode->frequency++; // increments `currentNode` frequency if `word` is the same as `currentNode->word`
}
return currentNode; // returns pointer to current node
}
/**
* @brief Reads words from file to tree
* @param file file to be read from
* @param root root node of tree
* @returns a pointer to the root node
*/
struct Node *readWordsInFileToTree(FILE *file, struct Node *root)
{
// longest english word = 45 chars
// +1 for '\0' = 46 chars
char *inputString =
(char *)malloc(46 * sizeof(char)); ///< pointer to the input string
char inputChar; ///< temp storage of characters
bool isPrevCharAlpha = false; ///< bool to mark the end of a word
uint8_t pos = 0; ///< position in inputString to place the inputChar
while ((inputChar = fgetc(file)) != EOF)
{
if (pos > 0)
isPrevCharAlpha = isalpha(inputString[pos - 1]);
// checks if character is letter
if (isalpha(inputChar))
{
inputString[pos++] = tolower(inputChar);
continue;
}
// checks if character is ' or - and if it is preceded by a letter eg
// yours-not, persons' (valid)
if ((inputChar == '\'' || inputChar == '-') && isPrevCharAlpha)
{
inputString[pos++] = inputChar;
continue;
}
// makes sure that there is something valid in inputString
if (pos == 0)
continue;
// if last character is not letter and is not ' then replace by \0
if (!isPrevCharAlpha && inputString[pos - 1] != '\'')
pos--;
inputString[pos] = '\0';
pos = 0;
isPrevCharAlpha = false;
root = addWordToTree(inputString, root);
}
// this is to catch the case for the EOF being immediately after the last
// letter or '
if (pos > 0)
{
if (!isPrevCharAlpha && inputString[pos - 1] != '\'')
pos--;
inputString[pos] = '\0';
root = addWordToTree(inputString, root);
}
free(inputString);
return root;
}
/**
* @brief Self-test implementations
* @returns void
*/
static void test()
{
struct Node *root = NULL; ///< pointer to the root node
FILE *file = NULL; ///< pointer to the file
file = fopen("file.txt", "w"); // creates test file in write mode
fprintf(file,
"hey_this, is a. test input \n to a_file"); // writes test data to
// test file
closeFile(file); // closes test file
file = fopen("file.txt", "r"); // reopens test file in read mode
root = readWordsInFileToTree(file,
root); // reads words from test file to tree
// Tests to check if words were added to correct position in tree and also
// if their frequencies were added correctly
assert(strcmp(root->word, "hey") == 0);
assert(root->frequency == 1);
assert(strcmp(root->left->word, "a") == 0);
assert(root->left->frequency == 2);
assert(strcmp(root->right->word, "this") == 0);
assert(strcmp(root->left->right->word, "file") == 0);
assert(strcmp(root->right->left->word, "is") == 0);
closeFile(file); // closes test file
remove("file.txt"); // deletes test file from storage
file = fopen("wordcount.txt", "a"); // creates write file
fprintf(file, "%-5s \t %9s \t %s \n", "S/N", "FREQUENCY",
"WORD"); // prints the heading to `wordcount.txt`
writeContentOfTreeToFile(
root, file); // writes content of tree to file (`wordcount.txt`)
// Here is how the output to `wordcount.txt` should look like
char *correctString =
"S/N FREQUENCY WORD \n"
"1 2 a \n"
"2 1 file \n"
"3 1 hey \n"
"4 1 input \n"
"5 1 is \n"
"6 1 n \n"
"7 1 test \n"
"8 1 this \n"
"9 1 to \n";
int16_t inputChar; // holds the current character in `wordcount.txt`
uint64_t i = 0; // holds the current index in `correctString`
// Checks if the content in `wordcount.txt` is as expected (the same as in
// `correctString`)
while ((inputChar = fgetc(file)) != EOF) {
assert(inputChar == correctString[i++]);
}
closeFile(file); // closes `wordcount.txt`
remove("wordcount.txt"); // deletes `wordcount.txt`
freeTreeMemory(root); // frees memory taken up by the tree
}
/**
* @brief Main function
* @returns 0 on exit
*/
int main()
{
test(); // run self-test implementations
return 0;
}