http:// proglit.com /

1. http://proglit.com/

2. the c language

3. SA BY

5. 1972 by Ken Thompson and Dennis Ritchie

6. developed concurrently with Unix C++ and Objective-C in 1980’s ANSI C89, C90, and C99 GCC (Gnu Compiler Collection) MSVC (Microsoft Visual C++)

7. http://proglit.com/

8. imperative/procedural • statically typed • weakly typed

9. control of memory explicitly manipulate individual bytes “portable assembly” compact data manual allocation

10. (how functions are called in machine code) calling convention assembly from C C from assembly

11. systems programming performance-sensitive code (operating systems, device drivers) (games, media players)

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13. basic data types char 1-byte signed integer intn-byte signed integer float single-precision floating-point double double-precision floating-point

14. declarations typename; int monkey; float zebra;

15. functions returnTypename(parameters) {body}

16. int square(int n) { return n * n; } int cube(int n) { return square(n) * n; }

17. char foo(int a, float b, float c) { … }

18. casting (type) expression int x = 35; foo((char) x);

19. http://proglit.com/

20. !0 // 1 !1 // 0 !0.6 // 0 !3 // 0 !-76.5 // 0

21. void roger(int x) { if (x == 3) { int z = 9; foo(z); } else { bar(z); // z does not exist } ack(z); // z does not exist }

22. void roger(int x) { int z = 9; if (x == 3) { foo(z); } else { bar(z); } ack(z); }

23. int main() { printf(“Hello, world!”); return 0; }

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25. value variables • float a = 9.3;

26. pointers (a data type representing an address) int*foo; double*bar; char*ack;

27. reference operator &lvalue char c; int*p; p = &c; // error inti; int*p; p = &i;

28. reference operator &lvalue char c; int*p; p = (int*) &c; inti; int*p; p = &i;

29. dereference operator *pointer inti = 3; int*p; p = &i; i = *p + 2;

30. int i; int*p; p = &i; *p = 6;

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32. pointer arithmetic inti; int*p; p = &i + 2; i = *p;

33. can subtracta pointer from a pointer can’t adda pointer to a pointer

34. char*p; p = (char*) 0xB000FFFF; char c = *p;

35. int*p; p = 0; if (p) { … } // false

36. pointer comparisons • == != • > < • >= <= • !

37. (can violate data types) weak typing float f; f = 98.6; f = f – 2; char*p; p = (char*)&f + 2; *p = 1;

38. http://proglit.com/

39. memory allocation malloc free

40. void*p; p = malloc(5); float*f; f = malloc(13); … free(p); free(f);

41. sizeof operator sizeoftype sizeof int sizeof double sizeof(float *)

42. int*p; p = malloc(7 * sizeof(int)); *(p + 6) = 35; … free(p);

43. int*p; p = malloc(7 * (sizeofint)); if (p == 0) { … // allocation failed } else { … // allocation succeeded free(p); }

44. http://proglit.com/

45. (a stack-allocated contiguous block of memory) array typename[size]; float jack[8]; char jill[200];

46. inti[32]; char c[11]; int *p; p = i; *i = -6; *(i + 1) = 8; *(c + 7) = (char) 5;

47. int sum(int *arr, int n) { int i = 0; int sum = 0; while (i < n) { sum = *(arr + i) + sum; i = i + 1; } return sum; }

48. int a[30]; … intsumA = sum(a, 30); • int *b = malloc(20 * sizeof(int)); • … • intsumB = sum(b, 20);

49. char *fred() { char c[30]; return c; }

50. char *fred() { • char*c = malloc(30 * sizeof(char)); return c; } char*foo = fred(); … free(foo);