1. Binary IO Writing and Reading Raw Data

2. Files Two major flavors of file: Text Binary

3. Text Files Text files – Easier to read by hand – Easier to reverse engineer – Easier to hand edit – More portable

4. Binary Files Binary files – More compact "2324223" = 7 ascii chars = 7 bytes (or more) 1 int = 4 bytes – Faster No conversions from strings to numbers Easier random access – Known size for numerics

5. Working in Binary Mode Can specify binary more when opening a file

6. Working in Binary Mode Binary IO : n bytes starting at address s – Address expressed as char * char = 1 byte

7. Writing Write c-string:

8. Results Outputting ascii chars… Hex editor: Good text editor:Notepad:

9. Writing Non-Chars Write other types: – Get pointer to data – Cast as a char* – Use sizeof( ) to calculate number of bytes

10. Cast Types Static_cast sanity checks types Reinterpret_cast sanity checks size C-Style cast picks whichever

11. Cast Types Static_cast sanity checks types Reinterpret_cast sanity checks size C-Style cast picks whichever

12. Results Outputting ascii followed by bits for 15 (F) Hex editor: Good text editor:Notepad:

13. Size Int = 4 bytes

14. Results Outputting 15 (F 16 ) followed by 258 (102 16 )

15. Endianess Endianess : bytes order of a word in main memory

16. Little vs Big Endian Big is "Normal": Little weird – Words in order – Bytes in a word backwards

17. Results Outputting 15 (F 16 ) followed by 258 (102 16 ) Little Endian ArrangementMeaning 0F00 0F Little Endian ArrangementMeaning 020100 0102

18. Reading Need to read string, 2 ints – String unknown length

19. Reading Read string char by char:

20. Reading Same, using c-string

21. Reading Reading two ints:

22. Complex Files Graphic/Sound/etc… files have defined structure:

23. Other Option Structured text : XML – Less efficient than text – Machine parseable – Wide collection of tools