count words in multiple files (C)

countWords.c

/*
 * File: driver2.c
 * YOUR NAME ... YOU NEED TO IMPLEMENT THE FUNCTIONS HERE....
 *
 * ....
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "myio.h"

char *removeSpaces(char *input);

int countWordsSingleFile(char *fileName);
int countWords(char *str);


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

   pid_t childPid, wpid;
   int status = 0;
   int totalCount = 0;

   if (argc < 2) {
      perror("Usage: driver2 input_file.txt");
      return -EINVAL;
   }


   //Father code (before child processes start)
   for (int id = 1; id < argc; id++) {
       if ((childPid = fork()) == 0) {
         //child code

         totalCount = countWordsSingleFile(argv[id]);
         if (totalCount > 0)
            printf("Child process %d for file %s: totalCount=%d\n", childPid, argv[id], totalCount);
         else if (totalCount == -ENOENT)
            printf("Child process %d for file %s: file doesn't exist\n", childPid, argv[id]);


         exit(0);
       }
   }

   while ((wpid = wait(&status)) > 0); // this way, the father waits for all the child processes

   //Father code (After all child processes end)


   return 0;
}

int countWordsSingleFile(char *fileName) {
   FILE *fp;
   char *str;
   char *newstr;
   int count = 0;
   int total_count = 0;

   /* opening file for reading */
   fp = fopen(fileName, "r");
   if (fp == NULL) {
      //perror("Error opening file");
      return -ENOENT;
   }

   while (str = ReadLineFile(fp)) {
      /* writing content to stdout */

      if (str[0] == '\0')
           break;

      newstr = removeSpaces(str);
      count = countWords(str);
      //printf("count=%d, str=%s\n", count, newstr);
      total_count+=count;

      free(str);
      free(newstr);
   }
   fclose(fp);

   return total_count;
}


#define OUT 0
#define IN 1

// returns number of words in str
int countWords(char *str)
{
    int state = OUT;
    int wc = 0; // word count

    // Scan all characters one by one
    while (*str)
    {
        // If next character is a separator, set the
        // state as OUT
        if (*str == ' ' || *str == '\n' || *str == '\t')
            state = OUT;

        // If next character is not a word separator and
        // state is OUT, then set the state as IN and
        // increment word count
        else if (state == OUT)
        {
            state = IN;
            ++wc;
        }

        // Move to next character
        ++str;
    }

    return wc;
}


char *removeSpaces(char *input) {
    int i = 0, j, n = strlen(input);
    while (i < n)
    {
        if(((input[i]==' ') && (input[i+1] == ' ' || input[i-1] == ' ')) ||
                                            ((input[i]==' ') && i == n-2)||
                                            ((i == 0) && (input[i]==' ')))
        {
            for(j=i; j<n; j++)
              input[j]=input[j+1];
            n--;

        }
        else
        {
            i++;
        }
    }

    n = strlen(input);
    if (input[n-1] != '\n')
        input[n] = '\n';

    return strdup(input);
}