#define _POSIX_C_SOURCE 200809L
#include <stdio.h>
#include <stdlib.h>

#define FILENAME "output.txt"

int write_file()
{
    FILE *handle;

    handle = fopen(FILENAME, "w");
    if (!handle)
    {
        perror("open file for writing");
        return 1;
    }

    fputs("A line of text\n", handle);
    fputs("Another line of text\n", handle);

    fclose(handle);
    return 0;
}

int read_file()
{
    char *line = NULL;
    ssize_t read;
    size_t len = 0;
    FILE *handle;

    handle = fopen(FILENAME, "r");
    if (!handle)
    {
        perror("open file for reading");
        return 1;
    }

    while ((read = getline(&line, &len, handle)) != -1)
        printf("%s", line);

    fclose(handle);
    free(line);

    return 0;
}

int main(int argc, char **argv)
{
    int rc;

    rc = write_file();
    if (rc != 0)
        return EXIT_FAILURE;

    rc = read_file();
    if (rc != 0)
        return EXIT_FAILURE;

    return EXIT_SUCCESS;
}