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ecs30 Winter 2012: Programming and Problem Solving #01: Chapters 1~2

ecs30 Winter 2012: Programming and Problem Solving #01: Chapters 1~2. Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu. About the Instructor. S. Felix Wu wu@cs.ucdavis.edu Facebook group: ecs30

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ecs30 Winter 2012: Programming and Problem Solving #01: Chapters 1~2

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  1. ecs30 Winter 2012:Programming and Problem Solving#01: Chapters 1~2 Dr. S. Felix Wu Computer Science Department University of California, Davis http://www.cs.ucdavis.edu/~wu/ wu@cs.ucdavis.edu ecs30 Winter 2012 Lecture #01

  2. About the Instructor • S. Felix Wu • wu@cs.ucdavis.edu • Facebook group: ecs30 • Office: 2109 Watershed • Phone: 919.443.5398 (Google Voice) • Office Hours: • 1-2 p.m. on Tue/Fri • by appointment ecs30 Winter 2012 Lecture #01

  3. ecs30 Winter 2012 Lecture #01

  4. ecs30 Winter 2012 Lecture #01

  5. Prerequisites • Math 16A or 21A (may be taken concurrently); prior experience with basic programming concepts (e.g., loop) recommended. ecs30 Winter 2012 Lecture #01

  6. Syllabus • Basic (1~2) • Function, Selection, & Repetition (3~6, 13) • Data Structure (7~9, 11, 14) • Recursion (10) • File (12) ecs30 Winter 2012 Lecture #01

  7. Problem Solving ecs30 Winter 2012 Lecture #01

  8. Course Requirements • 35%: Programming Assignments • 40%: Two close-book/note midterms • 25%: One close-book/note final ecs30 Winter 2012 Lecture #01

  9. Grading • I will give +/- grades. • possible grading : • A: >= 92 A-: >= 89 B+: >= 85 • B: >= 82 B-: >= 79 C+: >= 75 • C: >= 72 C-: >= 69 D+: >= 65 • D: >= 62 D-: >= 59 ecs30 Winter 2012 Lecture #01

  10. ecs30 is really about how to communicate with… ecs30 Winter 2012 Lecture #01

  11. ecs30 Winter 2012 Lecture #01

  12. ecs30 Winter 2012 Lecture #01

  13. #include <stdio.h> int main () { intx; /* declare x */ x = 1; printf("Hello world %d\n", x); return 0; }// main() ecs30 Winter 2012 Lecture #01

  14. Computer Programming basics • Computer Organization: • CPU (Central Processing Unit), Memory (mail box cells), I/O (Input Output devices) • Program: • A sequence of commands together achieving one goal. • Programming Language: • the language human use to communicate with computers. BTW, human use "natural languages" (e.g., English, Chinese...) to communicate among themselves. In this class, we learn how to use C to communicate with a Computer. • Compiler: • a tool that translates a program written in a high-level programming language into assembly/machine codes (low level). We need a C compiler (gcc) for C programs. ecs30 Winter 2012 Lecture #01

  15. ecs30b Fall 2008 Lecture #02

  16. ecs30b Fall 2008 Lecture #03

  17. { … } • { … } • {… { … {…}…} … {…}…} • int main (void) { … } • float myfunc (int x) { …; return f;} • { <declarations> <statements> } ecs30b Fall 2008 Lecture #02

  18. ecs30 winter 2012 Lecture #02

  19. printf("Hello world %d\n", x); scanf(“%lf”, &miles); Try this yourself – intx = 999; printf("Hello [%d %d]\n", x, &x); ecs30 winter 2012 Lecture #02

  20. Do I need to know exactly where to store/save the value of the variable “miles”? ecs30 winter 2012 Lecture #02

  21. ecs30b Fall 2008 Lecture #02

  22. Memory Cell Concept Again ecs30b Fall 2008 Lecture #02

  23. “Address” • Linguistics in C programming Language Where is THIS really located on my device? Then, we need a way to represent “address”! ecs30 winter 2012 Lecture #02

  24. “Address” • 32 bits or 64 bits address 01101001 10110001 11100000 10100111 0x69b1e0a7 ecs30 winter 2012 Lecture #02

  25. ecs30 Winter 2012 Lecture #01

  26. Binary Representation • Integer (int) 4 bytes • intx; • Double 8 bytes • double miles; • Character 1 byte • char c; • And, it depends on OS and hardware… ecs30 winter 2012 Lecture #03

  27. American Standard Code for Information Interchange ecs30 Winter 2012 Lecture #01

  28. ecs30 Winter 2012 Lecture #01

  29. Information Representation: We need Memory to store both Programs/Data. But How? bit: 0/1 physical memory. (BInary digiT) byte: 8 bits word: 32 bits Numbers (Decimal/Binary/Hexadecimal): How do we use bits to represent an integer. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ===> Decimal 0, 1 ===> Binary 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f ===> Hexadecimal ecs30b Fall 2008 Lecture #02

  30. Numbers: Base: 10, 2, 16 Binary {0,1} 0,1,2,3,4,5,6,7,8,9, 10,11, 0,1,2…,10,11,12,…99,100,101,102,… 0,1,10 (2), 11(3), 100 (4), 101(5), 110(6), 4 2 1 22, 21, 20 1 0 0 1 0 + 1 1 0 ecs30b Fall 2008 Lecture #02

  31. 0+1 = 1 1 20 1+1 = 10 2 21 10+1 = 11 3 11+1 = 100 4 22 100+1 = 101 5 101+1 = 110 6 110+1 = 111 7 111+1 = 1000 8 23 9 = 1+8 0001 1000 1001 001 010 100 111 001 100 101 7=1+2+4 5 = 1 + 4 ecs30b Fall 2008 Lecture #02

  32. ecs30 Winter 2012 Lecture #01

  33. 210 21 ecs30 Winter 2012 Lecture #01

  34. 210 29 28 27 23 24 25 26 24 +24 22 24 22 21 ecs30 Winter 2012 Lecture #01

  35. 210 29 28 27 23 24 25 26 24 +24 22 24 22 24 *24 21 ecs30 Winter 2012 Lecture #01

  36. 0 = 0000 = 0 * 8 + 0 * 4 + 0 * 2 + 0 * 1 1 = 0001 = 0 * 8 + 0 * 4 + 0 * 2 + 1 * 1 2 = 0010 = 0 * 8 + 0 * 4 + 1 * 2 + 0 * 1 3 = 0011 = 0 * 8 + 0 * 4 + 1 * 2 + 1 * 1 ....... 7 = 0111 = 0 * 8 + 1 * 4 + 1 * 2 + 1 * 1 8 = 1000 = 1 * 8 + 0 * 4 + 0 * 2 + 0 * 1 9 = 1001 = 1 * 8 + 0 * 4 + 0 * 2 + 1 * 1 10 (a) = 1010 = 1 * 8 + 0 * 4 + 1 * 2 + 0 * 1 11 (b) = 1011 = 1 * 8 + 0 * 4 + 1 * 2 + 1 * 1 12 (c) = 1100 = 1 * 8 + 1 * 4 + 0 * 2 + 0 * 1 13 (d) = 1101 = 1 * 8 + 1 * 4 + 0 * 2 + 1 * 1 14 (e) = 1110 = 1 * 8 + 1 * 4 + 1 * 2 + 0 * 1 15 (f) = 1111 = 1 * 8 + 1 * 4 + 1 * 2 + 1 * 1 Examples: 09FE (in Hex) == ? (in Binary) == ? (in Decimal) ecs30b Fall 2008 Lecture #02

  37. “Memory Box” Each “address-able” box is ONE Byte 1 byte = 8 bits 1 bit is 0 or 1 Binary representation ecs30 Winter 2012 Lecture #01

  38. Bytes • 1 byte == 8 bits • 1 K bytes = 1024 = 210 • 1 M bytes = 1024 * 1024 = 220 • 1 G bytes = 230 • 1 T bytes = 240 • 1 Pbytes = 250 ecs30 Winter 2012 Lecture #01

  39. “The story of X” int X; X, &X, *X, ((struct S *) X)->index, ((int *) X)[20], *(((int *) X)+20), ((double *) X)[20], ((struct S *) 0)->index,… ecs30 Winter 2012 Lecture #01

  40. Byte versus Double • Each Memory cell is 1 Byte • How about Double? • How will Double map to your hardware memory? ecs30 winter 2012 Lecture #02

  41. Arithmetic Operations in Binary/Bits? +/- 0001 + 0001 = 0010 bit: 0/1 physical memory. byte: 8 bits in Unix, “usually” an integer has 4 bytes, i.e., 32 bits. unsigned 0 ~ 4294967295 (i.e. 2 32 -1) signed -2147483648 ~ 2147483647 (i.e. -(231) ~ (231 - 1)) ecs30 winter 2012 Lecture #02

  42. How do I represent a character? (Internal coding) ASCII (American Standard Code for Information Interchange) use 7 bit to represent a character (might or might not on your keyboard) Example: 'A' 1100001 (in Byte, 0110001) (Appendix A: page 839) Decimal: 65, Hex: 41. Question: How many different characters can we represent? ecs30 winter 2012 Lecture #02

  43. Binary Representation • Integer (int) 4 bytes • Double 8 bytes • Character 1 byte ecs30 winter 2012 Lecture #02

  44. /* an example program for the sizeof operator in C */ #include <stdio.h> main() { printf("The size of an integer is %d.\n", sizeof(int)); printf("The size of a float is %d.\n", sizeof(float)); printf("The size of a double is %d.\n", sizeof(double)); printf("The size of a character is %d.\n", sizeof(char)); } The size of an integer is 4. The size of a float is 4. The size of a double is 8. The size of a character is 1. ecs30 winter 2012 Lecture #02

  45. Int 4 bytes 0000 0000 0000 0000 0000 0000 0000 0000 1111 1111 1111 1111 1111 1111 1111 1111 ecs30 Winter 2012 Lecture #01

  46. Character /* an example program for the sizeof operator in C */ #include <stdio.h> int main(void) { printf("The size of an integer is %d.\n", sizeof(int)); printf("The size of a float is %d.\n", sizeof(float)); printf("The size of a double is %d.\n", sizeof(double)); printf("The size of a character is %d.\n", sizeof(char)); } Output: The size of an integer is 4. The size of a float is 4. The size of a double is 8. The size of a character is 1. ecs30 winter 2012 Lecture #03

  47. printf("value = %d, address = %d\n", cats, &cats); ===> value = 3, address = -268438156; **** printf("value = %d, address = %x\n", cats, &cats); ===> value = 3, address = effff574; -268438156 (in decimal) == effff574 (in hex) aa = -268438156; aa = 0xeffff574; ecs30 winter 2012 Lecture #02

  48. ecs30 winter 2012 Lecture #02

  49. My Experience … • How we learn to communicate with a Computer in C. • you will not know everything clearly at one time. • you will never learn if you do not try. • you will observe the results from your trying. • you should observe the C examples in the textbook and how this language is used in various situations. You might not know why it is used “this” way (even after I explain to you), but just try to use it the same way in the examples. you will learn eventually. • In general, there is no short cut. ecs30 Winter 2012 Lecture #01

  50. Compile your first program • emacs • gcc • make • a.out ecs30 Winter 2012 Lecture #01

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