[c] Get filesize

file_sizeof.c

/* Returns file size in BYTES */                                                                                                                                                                
int file_sizeof(FILE *fp)                                                                                                                                                                       
{                                                                                                                                                                                               
     int filesize;                                                                                                                                                                              
     fseek(fp, 0L, SEEK_END); /* jump to end of file */                                                                                                                                         
     filesize = ftell(fp);    /* current byte of file == filesize */                                                                                                                            
     rewind(fp);              /* jump to beginning of file */                                                                                                                                   
     return filesize;                                                                                                                                                                           
}

int main(){
    FILE *fp;
    char *filename = "file.dat";
    int filesize;
    fp = fopen(filename,"wb") /* check if not NULL */
    filesize = file_sizeof(fp);
    printf("size of %s is %d\n", filename, filesize);

    return 0;
}