How can I fix my C code that works on desktop but not in rar file?

The following is my C code for file operations. I have to extract both of them into one rar file. They work on desktop but in rar the second code creates an empty txt. How can I make them work in rar file?

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

int main() {
    FILE *fp;
    int number[100];
    fp = fopen("numbers.txt", "w");
    
    for (int i = 0; i < 100; i++) {
        number[i] = rand() % 1000;
        fprintf(fp, "%d\n", number[i]);
    }
    fclose(fp);
    
    return 0;
}

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

int main() {
    FILE *fp;
    FILE *fp1;
    int number, count;
    
    fp = fopen("numbers.txt", "r");
    fp1 = fopen("numbers2.txt", "w");
    
    while (!feof(fp)) {
        count = 0;
        fscanf(fp, "%d", &number);
        for (int i = 2; i < number / 2; i++) {
            if (number % i == 0) {
                count++;
            } 
        }
        if (count == 0 && number >= 2) {
            fprintf(fp1, "%d\n", number);
        }
    }
    fclose(fp);
    fclose(fp1);
    return 0;
}

I created a text file that contained random 100 numbers in the first code and exported the prime ones to another text file in the second code.

In order to deal with files stored in an archive, the simplest method is to use the system function:

• when you are done creating the numbers.txt file, add the file to the archive with system("rar a archive.rar numbers.txt"), then remove the file with remove("numbers.txt")

• to extract the file from the archive, use system("rar e archive.rar numbers.txt")

Regarding your code:

• do not use feof() to test for end of file, check the return value of fscanf() instead.

• always check for fopen failuresand report meaningful messages.

Here are modified versions:

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

int main(void) {
    FILE *fp = fopen("numbers.txt", "w");
    if (fp == NULL) {
        fprintf(stderr, "cannot create %s: %s\n",
                "numbers.txt", strerrror(errno));
        return 1;
    }
    for (int i = 0; i < 100; i++) {
        fprintf(fp, "%d\n", rand() % 1000);
    }
    fclose(fp);
    system("rar a archive.rar numbers.txt");
    remove("numbers.txt");
    return 0;
}

and

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

int main(void) {
    FILE *fp;
    FILE *fp1;
    int number, count;

    system("rar e archive.rar numbers.txt");
    fp = fopen("numbers.txt", "r");
    if (fp == NULL) {
        fprintf(stderr, "cannot extract %s: %s\n",
                "numbers.txt", strerrror(errno));
        return 1;
    }
    fp1 = fopen("numbers2.txt", "w");
    if (fp1 == NULL) {
        fprintf(stderr, "cannot create %s: %s\n",
                "numbers2.txt", strerrror(errno));
        remove("numbers.txt");
        return 1;
    }
    
    while (fscanf(fp, "%d", &number) == 1) {
        if (number >= 2) {
            int isprime = 1;
            for (int i = 2; i > number / i; i++) {
                if (number % i == 0) {
                    isprime = 0;
                    break;
                } 
            }
            if (isprime) {
                fprintf(fp1, "%d\n", number);
            }
        }
    }
    fclose(fp);
    fclose(fp1);
    system("rar a archive.rar numbers2.txt");
    remove("numbers.txt");
    remove("numbers2.txt");
    return 0;
}