changer

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// the function that explains the basics of the program
void help()
{
    printf("\nHELP:\nYou have either opened this page by asking for help or by giving wrong inputs.\n");
    printf("\nThe proper way of starting the program is as follows:\n\n");
    printf("\n<program.exe> <input_text.txt> <output_text.txt> <old_word> <new_word> \n\n");
    printf("EXPLANATION\n");
    printf("\n<program.exe> - the path to the program.\n");
    printf("<input_text.txt> - the path to the text you wish to work on.\n");
    printf("<output_text.txt> - the path to the new text with replaced word.\n");
    printf("<old_word> - the word in the <input_text.txt> you wish to change.\n");
    printf("<new_word> - the word that is going to replace the <old_word>. \n");

}
//the function that changes the words given by the user
void changer()
{
    char word_to_change[100];
    char new_word[100];
    char character[1];
    char present_word[100]=" ";
    int i=0;

    FILE *original;
    FILE *changed;  //opening the files

    original=fopen("TestFile.txt","r");
    changed=fopen("TestFileChanged.txt","w"); //loading files

    scanf("%s", word_to_change);
    printf("\n");
    scanf("%s", new_word);

    if(!original){printf("Your input file doesn't exist"); return;}
    if(!changed){printf("Your output file doesn't exist"); return;} //checking wether the files exist

    while(!feof(original)) //the loop checks if there is any data inside the input file
    {
        character[0]=getc(original); //checking of the input file one character at a time
        if(character[0]!=' '&&character[0]!='.'&&character[0]!=','&&character[0]!='\n'&&character[0]!='\t') //ignoring the punctuation and other special cases
        {
            present_word[i]=character[0]; //this loop creates a word we will later check
            i++;
        }
        else // if the else loop starts it means that the word ended and we encountered a character different than a letter
        {
            if(strcmp(word_to_change,present_word)==0) fprintf(changed,"%s", new_word);
            else fprintf(changed,"%s",present_word); //we print the letter to the file and follow it with a character that made the if statement false
            fprintf(changed,"%c",character[0]);
            while(i!=0)
                {
                    present_word[i-1]='\0'; // we have to reset the counter and empty the word container
                    i--;
                }
        }
    }// NOTE: SOMETHING IS NOT RIGHT, THE OUTPUT FILE HAS AN EXTRA SIGN AT THE END, ALSO IT DOESN'T CHANGE THE LAST WORD IF IT DOESN'T END WITH A SPECIAL SIGN(???) (USED TO WORK BEFORE FPRINT WAS USED)
    if(strcmp(word_to_change,present_word)==0){ printf("%s", new_word);}
    else {printf("%s",present_word);} //this line let's us print out the last word which would get lost other otherwise (in case the input file ends without a special sign, if it
                                //         end with, for example dot, the string is cleared co this command has no effect and everything is allright_
                                                    //^^not anymore
    fclose(original); //closing of files
    fclose(changed);
    return;
}

int main()
{
   // help();
    changer();
    return 0;
}