#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

/* Different ways to get filesizes, some are linux-specific (i think), some are posix */

void file_tell(void);
void file_stat(void);
void file_end(void);

int main(void) {
    file_stat();
    file_tell();
    file_end();

    return EXIT_SUCCESS;
}

/* This works on linux, but may not be posix compliant */
void file_stat(void) {
    const char *filename = "filesize.c";
    struct stat st;

    if (stat(filename, &st) == 0) {
        printf("File size: %lld bytes\n", (long long)st.st_size);
    } else {
        perror("stat");
    }
}

/* This works on all posix systems afaik */
void file_tell(void) {
    FILE *f = fopen("filesize.c", "rb");
    if (!f) {
        perror("fopen");
        return;
    }

    fseek(f, 0, SEEK_END);
    long size = ftell(f);
    fclose(f);

    if (size >= 0) {
        printf("File size: %ld bytes\n", size);
    } else {
        perror("ftell");
    }
}

/* This is bad for obvious reasons*/
void file_end(void) {
    FILE *f = fopen("filesize.c", "rb");
    if (!f)
        return;

    size_t size = 0;
    while (fgetc(f) != EOF) {
        size++;
    }
    fclose(f);

    printf("File size: %zu bytes\n", size);
}