Various issues while dealing with files -C90

Question

The problem(actually various problems):

1. if choice != 0 either the insert_text function is called or add_word_in_dictionary is called which is not wanted..

2. I want to create a function which saves a file.Thus, I created the save_file function but I am not that sure if it actually 'saves' the file..

3. the count_difrnt_words function..With this function I want to count how many different words are in a file but I do not know the length of each string-word in the file so I guess fgets can't be used in this occasion..

The englishWords.txt is a large file with words like this https://prnt.sc/3BKsO7_Ud2XG

and the other file that is used,is a 'common' .txt file with words,special characters,spaces between words etc..

The code:

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


int get_choice(void);
int check_word(char *word);
void insert_text(FILE ** p_fp);
char *add_word(void);
void add_word_in_dictionary(FILE ** p_fp);
void save_file(FILE **fp);
int count_characters(FILE **fp);
int count_spaces(FILE **fp);


int main()
{
    FILE *fp;
    FILE *fp2;  /*fp for Alice....txt and fp2 for englishWords.txt */
    int choice = 0;
    while(1)
    {
        choice = get_choice();

        if(choice == 0)
        {
            insert_text(&fp);
        }

        if(choice == 1);
        {
            add_word_in_dictionary(&fp2);
        }

        if(choice == 2)
        {
            printf("\n You have entered correction mode but in this 
version, nothing happens \n");
        }

        if(choice == 3)
        {
            save_file(&fp);
            printf("\n The file has been saved \n");
        }

        if(choice == 4)
        {
            count_characters(&fp);
            count_spaces(&fp);
            count_difrnt_words(&fp);


        }

        if(choice == 5)
        {
            break;
        }

    }

    printf("\n The program has ended \n");
    return 0;
}



int get_choice(void) {
    int choice = 0;
    printf("\n Select a choice from  the below \n");
    printf("\n Select 0 to add text \n");
    printf("\n Select 1 to add new words in the dictionary \n");
    printf("\n Select 2 to enter  enter correction mode \n");
    printf("\n Select 3 to save the text \n");
    printf("\n Select 4 to see the statistics about your text \n");
    printf("\n Select 5 to exit the program\n");
    scanf("\n%d", &choice);
    return choice;
}



int check_word(char *word)
{
    FILE *readfile;
    char word1[40];
    readfile = fopen("englishWords.txt","r");

    if(!readfile)
    {
        printf("\n There was an error opening the file \n");
        return;
    }

    while(fscanf(readfile,"%s",word1) != EOF)
    {
        if(strcmp(word,word1) == 0)
        return 1;

        else
        {
            return 0;
        }
    }

    fclose(readfile);
}



void insert_text(FILE ** p_fp)
{
    *p_fp = fopen("AlicesAdventuresInWonderland.txt", "a+");
    fprintf(*p_fp, "%99s\n",add_word());
    return;
}



char *add_word(void)
{
    char string[100] = {""};
    printf("\n Please enter the word \n");
    scanf("\n%[^\n]", &string);
    return string;
}



void add_word_in_dictionary(FILE ** p_fp)
{
    *p_fp = fopen("englishWords.txt","a+");
    fprintf(*p_fp, "%99s\n",add_word());
    return;
}



 void save_file(FILE **fp)
{
    fclose(*fp);
    return;
}



int count_characters(FILE **fp)
{
    char ch;
    int count_ch = 0;
    *fp = fopen("AlicesAdventuresInWonderland.txt", "r");
    if(*fp == NULL)
    {
        printf("\n There was an error opening the file \n");
        return;
    }

    while(ch != EOF)
    {
        if(ch != ' '  && ch !=  '\n')
        {
            count_ch++;
        }
        ch=fgetc(*fp);
    }

    fclose(*fp);

    return count_ch;
}



int count_spaces(FILE **fp)
{
    int count_sp;
    char c;
    *fp = fopen("AlicesAdventuresInWonderland.txt","r");
     while ((c = fgetc(*fp)) != EOF)
    {
        if (c == ' ')
            count_sp++;
    }

    return count_sp;
}

int count_difrnt_words(FILE **fp)
{
    int i;
    int num = 0;
    char str[15];
    char c;
    *fp = fopen("AlicesAdventuresInWonderland.txt","r");
    while((c = fgetc(*fp)) != EOF)
        {
           fgets(str,15,*fp);
           if(strcmp(fgets(str,15,*fp),fgets(str,15,*(fp+i))))
        {
        num++;
        }

        i++;

    }

    return num;
}

Answer 1

Your add_word function return a pointer to a local variable. Local variables cease to exists immediately when the function ends (the life-time of the variable ends together with the function return).

Any pointer to a local variable will become invalid and can't be used. Using it anyway will lead to undefined behavior.

I suggest you change the add_word function to accept the array as an argument instead:

char *add_word(char *word)
{
    printf("\n Please enter the word \n");
    scanf(" %100[^\n]", word);
    return word;
}

This change means you have to change how you call it, and that the array needs to be defined in the calling function instead.

For example:

void insert_text(FILE ** p_fp)
{
    *p_fp = fopen("AlicesAdventuresInWonderland.txt", "a+");

    char word[100];
    fprintf(*p_fp, "%s\n", add_word(word));
}