C assignment help

C program. NOT C++
specialcountmulthreads.c is not completed. Need some modification

31 text files named input_00.txt to input_30.txt.


Multiple threads are expected to run in parallel to share the workload, i.e. suppose 3 threads to process 30 files totally, then each thread should process 10 files;

When a thread is created, a message should be print out showing which files this thread will process, for example:

Thread id = 274237184 starts processing files with index from 0 to 10!

When a file is being processed, a message should be print out showing which thread (thread_id = xxx) is processing this file, for example:

Thread id = 265844480 is processing file input_11.txt

When a thread is done with its workload, a message should be print out showing which files this thread has done with work, for example:

Thread id = 274237184 is done !

The array long specialfreq[ ] should always be up-to-date, i.e. it always has the result of all the threads counted so far. [You may need to use mutexes to protect this critical region.]


#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <string.h>

#include <pthread.h>

#define MAX_FILES 30

#define MAX_LEN 1000

int num_threads;

char *filename[MAX_FILES];

int num_files;

long specialfreq[MAX_FILES];

int *index_array[MAX_FILES];

void *thread_function(void *arg) {

int *index = (int *) arg;

int i;

int my_index = *index;

int starting_index = my_index * (num_files / num_threads);

int ending_index = starting_index + (num_files / num_threads);

FILE *fp;

char ch;

int count = 0;

char line[MAX_LEN];

printf("Thread ID: %lu starts working on files %d to %d.n", pthread_self(), starting_index, ending_index);

for (i = starting_index; i < ending_index; i++) {

fp = fopen(filename[i], "r");

if (fp == NULL) {

perror("Error opening file");

} else {

printf("Thread ID: %lu is working on file %sn", pthread_self(), filename[i]);

while (fgets(line, sizeof (line), fp) != NULL) {

ch = fgetc(fp);

if (ch == '!') {




specialfreq[i] = count;




printf("Thread ID: %lu is done!n", pthread_self());



void specialcountmulthreads(char *path, char *filetowrite, long specialfreq[], int num_threads) {

pthread_t tid;

int i;

int err;

int total_count = 0;

if (argc < 3) {

printf("Usage: ./a.out num_threads input_file1 input_file2 … input_file30");



num_threads = atoi(argv[1]);

num_files = argc – 2;

//printf("Num thread: %dn", num_threads);

//printf("Num files: %dn", num_files);

for (i = 2; i < argc; i++) {

filename[i – 2] = argv[i];

//printf("Argv: %sn", argv[i]);

//printf("Filename: %sn", filename[i – 2]);


for (i = 0; i < num_files; i++) {

index_array[i] = malloc(sizeof (int));

*index_array[i] = i;

//printf("Index array: %dn", *index_array[i]);

//printf("Index array: %dn", index_array[i]);


for (i = 0; i < num_threads; i++) {

err = pthread_create(&tid, NULL, thread_function, index_array[i]);

if (err != 0) {

printf("ncan't create thread :[%s]", strerror(err));



for (i = 0; i < num_files; i++) {

total_count += specialfreq[i];


printf("Total count: %dn", total_count);

return 0;



#include <stdio.h>

#include <dirent.h>

#include <string.h>

#include <stdlib.h>

#include <ctype.h>


#include <stdbool.h>

#include "count.h"


* Print the frequencies of special words stored in array: specialfreq[] to output screen in the format as:

* letter -> frequency (one letter a line)

* Input: specialfreq – array having the frequency of each special word

size – the total number of special words

* example:

* he -> 250932

* she -> 181764


void displayalphabetfreq(long specialfreq[], int size)


for(int i = 0; i < size; i++)


switch (i)


case 0:

printf("%s -> %dn", "he", specialfreq[i]);


case 1:

printf("%s -> %dn", "she", specialfreq[i]);


case 2:

printf("%s -> %dn", "they", specialfreq[i]);


case 3:

printf("%s -> %dn", "him", specialfreq[i]);


case 4:

printf("%s -> %dn", "me", specialfreq[i]);



printf("%s", "Wrong number of special words … ");




int main(int argc, char *argv[])


printf("Please enter 2 arguments only eg."./testmulthreads #_of__threads!!"n");

int num_threads = atoi(argv[1]);

char *path = "../data"; // the data *.txt files are under this folder

char *filetowrite = "../result/result.txt"; // the frequency of all alphabetical letters will be written in this file

long specialfreq[SPECIALSIZE] = {0}; // array to store the frequency of each alphablet letter, which should be alway up-to-date;

specialcountmulthreads(path, filetowrite, specialfreq, num_threads); // process the data files using mutiple threads

printf("The results are counted as follows : n");

displayalphabetfreq(specialfreq, SPECIALSIZE); // print the frequency stored in the array to output screen


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