#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#define FILE_PATH "/tmp/anyfile"

struct record {
    uint8_t id;
    uint8_t type;
    uint8_t source;
    char body[32];
};

int main ()
{
    struct record any_record = {.id = 2, .type = 4, .source = 33, .body = "Hello"};
    uint16_t another_stuff = 12; // Different compiler have different implementation of int, however uint16_t mitigites such problem
    FILE* that_file;

    // Blank line: seperates the declaration and program
    that_file = fopen(FILE_PATH, "w");
    if (NULL == that_file) {
        // why NULL == that_file?
        // if the program made a typo of "NULL = that_file", it works actually
        printf("Sorry, failed to open file.\n");
        return -1;
    }

    // put an record to the file
    fwrite(&any_record, sizeof(any_record), 1, that_file);
    fflush(that_file);
    fclose(that_file);
    return 0;
}