High-Order Language APPLICATION LEVEL HIGH-ORDER LANGUAGE LEVEL ASSEMBLY LEVEL OPERATING SYSTEM LEVEL INSTRUCTION SET ARCHITECTURE LEVEL

Transcription

1 Chapter 2 C

2 High-Order Laguage APPLICATION LEVEL HIGH-ORDER LANGUAGE LEVEL 6 ASSEMBLY LEVEL OPERATING SYSTEM LEVEL INSTRUCTION SET ARCHITECTURE LEVEL MICROCODE LEVEL LOGIC GATE LEVEL

3 Figure Applicatio level High-order laguage level Assembly level Operatig system level Istructio set architecture level Microcode level Logic gate level

4 Figure 2.2 Iput Source program Processig Compiler Output Object program

5 Figure 2. C source program Brad X C compiler Brad Y C compiler Brad X object program Brad Y object program

6 The C memory model Global variables fixed locatio i memory Local variables ad parameters ru-time stack Dyamically allocated variables heap

7 Fuctio call Push storage for the retur value Push the actual parameters Push the retur address Push storage for the local variables

8 Fuctio retur Pop the local variables Pop the parameters Pop the retur value Pop the retur address

9 Three attributes of a Name Type Value C variable

10 Figure 2.4 // Sta Warford // A osese program to illustrate global variables. #iclude <stdio.h> char ch; it j; it mai() { scaf("%c %d", &ch, &j); j += 5; ch++; pritf("%c\%d\", ch, j); retur 0; Iput M 49 Output N 424

11 Variables Global Declared outside of mai() Local Declared withi mai()

12 Figure 2.5 ch N ra0 j (a) Fixed locatio. (b) Ru-time stack.

13 Figure 2.6 #iclude <stdio.h> it mai() { cost it bous = 0; it exam; it exam2; it score; scaf("%d %d", &exam, &exam2); score = (exam + exam2) / 2 + bous; pritf("score = %d\", score); retur 0; Iput Output score = 86

14 Figure 2.7 Expressio Value Expressio Value 5 / 5 5 % 0 4 / 4 4 % 2 / 4 % 2 / 4 2 % 0 / % 2

15 Figure 2.8 score score exam2 exam2 84 exam exam 64 ra0 ra0 (a) Before the iput statemet executes. (b) After the iput statemet executes.

16 Figure 2.9 Operator Meaig == Equal to < Less tha <= Less tha or equal to > Greater tha >= Greater tha or equal to!= Not equal to

17 Figure 2.0 #iclude <stdio.h> it mai() { cost it limit = 00; it um; scaf("%d", &um); if (um >= limit) { pritf("high\"); else { pritf("low\"); retur 0; Iput 75 Output low

18 Figure 2. Symbol && Meaig AND OR! NOT

19 Figure 2.2 #iclude <stdio.h> it mai() { it guess; pritf("pick a umber 0..: "); scaf("%d", &guess); switch (guess) { case 0: pritf("not close\"); break; case : pritf("close\"); break; case 2: pritf("right o\"); break; case : pritf("too high\"); retur 0; Iteractive Iput/Output Pick a umber 0..: Close

20 Figure 2. #iclude <stdio.h> char letter; it mai() { scaf("%c", &letter); while (letter!= '*') { if (letter == ' ') { pritf("\"); else { pritf("%c", letter); scaf("%c", &letter); retur 0; Iput Hello, world!* Output Hello, world!

21 Figure 2.4 #iclude <stdio.h> it cop; it driver; it mai() { cop = 0; driver = 40; do { cop += 25; driver += 20; while (cop < driver); pritf("%d", cop); retur 0; Output 200

22 Figure 2.5 #iclude <stdio.h> it vector[4]; it j; it mai() { for (j = 0; j < 4; j++) { scaf("%d", &vector[j]); for (j = ; j >= 0; j--) { pritf("%d %d\", j, vector[j]); retur 0; Iput Output

23 Allocatio process for a void fuctio Push the actual parameters Push the retur address Push storage for the local variables

24 Deallocatio process for a void fuctio Pop the local variables Pop the parameters Pop the retur address

25 Figure 2.6 #iclude <stdio.h> it umpts; it value; it j; void pritbar(it ) { it k; for (k = ; k <= ; k++) { pritf("*"); pritf("\"); it mai() { scaf("%d", &umpts); for (j = ; j <= umpts; j++) { scaf("%d", &value); pritbar(value); //ra retur 0;

26 Figure 2.6 (cotiued) Iput Output *** ************* ***************** ********************************** *************************** *********************** ************************* ***************************** **************** ********** **

27 Figure 2.7 umpoits umpoits 2 value ra0 value ra0 j j (a) Begi (b) scaf("%d", &umpts) umpoits 2 umpoits 2 value ra0 value ra0 j j (c) for(j = ; j <= umpoits; j++) (d) scaf("%d", &value)

28 Figure 2.7 (cotiued) ra umpoits 2 umpoits 2 value ra0 value ra0 j j (e) Push formal parameter (f) Push retur address k ra umpoits 2 value ra0 j (g) Push storage for local variable k

29 Figure 2.8 #iclude <stdio.h> it um; it fact(it ) { it f, j; f = ; for (j = ; j <= ; j++) { f *= j; retur f; it mai() { pritf("eter a small iteger: "); scaf("%d", &um); pritf("its factorial is: %d\", fact(um)); // ra retur 0; Iteractive Iput/Output Eter a small iteger: Its factorial is: 6

30 Figure 2.9 ra0 ra0 um um (a) Begi (b) scaf("%d", &um) ra0 um um ra0 (c) Push storage for retur value i (d) Push actual parameter

31 ra ra0 um um ra ra0 Figure 2.9 (cotiued) f (e) Push retur address (f) Push storage for local variable f j f ra ra0 um um ra ra0 j f (g) Push storage for local variable j (h) f =

32 Call by referece I call by value, the formal parameter gets the value of the actual parameter. If the formal parameter chages, the actual parameter does ot chage. I call by referece, the formal parameter gets a referece to the actual parameter. If the formal parameter chages, the actual parameter does chage.

33 Figure 2.20 #iclude <stdio.h> it a, b; void swap(it *r, it *s) { it temp; temp = *r; *r = *s; *s = temp; void order(it *x, it *y) { if (*x > *y) { swap (x, y); // ra2 it mai() { pritf("eter a iteger: "); scaf("%d", &a); pritf("eter a iteger: "); scaf("%d", &b); order (&a, &b); pritf("ordered they are: %d, %d\", a,b); // ra retur 0;

34 Figure 2.20 (cotiued) Iteractive Iput/Output Eter a iteger: 6 Eter a iteger: 2 Ordered they are: 2, 6

35 Figure 2.2 b a ra0 b a 2 6 ra0 (a) Begi (b) Iput a, b

36 Figure 2.2 (cotiued) temp ra2 s r ra ra y y x x b 2 ra0 b 2 ra0 a 6 a 6 (c) order(&a, &b) (d) swap(x,y)

37 Figure 2.2 (cotiued) ra y x b 6 ra0 b 6 ra0 a 2 a 2 (e) Retur from swap() (f) Retur from order()

38 Figure 2.22 #iclude <stdio.h> it um; it fact(it ) { if ( <= ) { retur ; else { retur * fact( - ); // ra2 it mai() { pritf("eter a small iteger: "); scaf("%d", &um); pritf("its factorial is: %d\", fact(um)); // ra retur 0; Iteractive Iput/Output Eter a small iteger: 4 Its factorial is: 24

39 Figure 2.2 um 4 4 ra 4 (a) Begi (b) scaf("%d", &um) (c) Call fact (4)

40 Figure 2.2 (cotiued) ra2 ra2 ra2 2 2 ra2 ra2 ra2 ra ra ra um (d) Call fact () (e) Call fact (2) (f) Call fact ()

41 Figure 2.2 (cotiued) ra2 ra2 2 ra2 ra 4 um 4 4 ra2 2 2 ra2 ra 4 4 ra2 6 ra 4 (g) Compute (h) Retur (i) Retur

42 Figure 2.2 (cotiued) um ra (j) Retur (k) Retur

43 Figure 2.24 Mai program fact(4) 24 fact() fact(2) fact() 6 2

44 Figure 2.25 #iclude <stdio.h> it list[4]; it sum(it a[], it ) { // Returs the sum of the elemets of a betwee a[0] ad a[]. if ( == 0) { retur a[0]; else { retur a[] + sum(a, - ); // ra2 it mai() { pritf("eter four itegers: "); scaf("%d %d %d %d", &list[0], &list[], &list[2], &list[]); pritf("their sum is: %d\", sum(list, )); retur 0; Iteractive Iput/Output Eter four itegers: Their sum is: 5

45 Figure 2.26 ra2 2 a list[0] list[] list[2] list[] list[0] list[] list[2] list[] ra a list[0] list[] list[2] list[] ra a (a) Iput list (b) Call sum (list, ) (c) Call sum (list, 2)

46 Figure 2.27 Term umber, k Power,

47 Figure 2.28 #iclude <stdio.h> it bicoeff(it, it k) { it y, y2; if ((k == 0) ( == k)) { retur ; else { y = bicoeff( -, k); // ra2 y2 = bicoeff( -, k - ); // ra retur y + y2; it mai() { pritf("bicoeff(, ) = %d\", bicoeff(, )); // ra retur 0; Output bicoeff(, ) =

48 Figure 2.29 y2 y ra2 k y2 y2 y2 y y y ra2 ra2 ra2 k k k ra y2 y k ra y2 y k ra y2 y k ra y2 y k (a) Begi (b) Call BC (, ) (c) Call BC (2, ) (d) Call BC (, ) (e) Retur

49 Figure 2.29 (cotiued) y2 y ra 0 k y2 y2 y2 y y y ra2 ra2 ra k k 0 k y2 y2 y2 y2 y2 y y 2 y 2 y 2 y ra ra ra ra ra k k k k k (f) Call BC (, 0) (g) Retur (h) Retur (i) Call BC (2, 0) (j) Retur (k) Retur

50 Figure 2.0 Mai program Call BC(,) Call BC(2,) Call BC(,) Retur to BC(2,) Call BC(,0) Retur to BC(2,) Retur to BC(,) Call BC(2,0) Retur to BC(,) Retur to mai program Mai program BC (, ) 2 BC (2, ) BC (, ) BC (, 0) BC (2, 0)

51 Figure 2.

52 Figure 2.2 #iclude <stdio.h> void reverse(char *str, it j, it k) { char temp; if (j < k) { temp = str[j]; str[j] = str[k]; str[k] = temp; reverse(str, j +, k - ); // ra2 it mai() { char word[5] = "star"; pritf("%s\", word); reverse(word, 0, ); pritf("%s\", word); // ra retur 0; Output star rats

53 Figure 2. temp ra 2 k j str temp 's' temp 's' temp ra ra ra k k k 0 j 0 j 0 j str str str 's' word[0] 's' word[0] 'r' word[0] 'r' word[0] 't' word[] 't' word[] 't' word[] 't' word[] 'a' word[2] 'a' word[2] 'a' word[2] 'a' word[2] 'r' word[] 'r' word[] 's' word[] 's' word[] '\0' word[4] '\0' word[4] '\0' word[4] '\0' word[4] ra0 ra0 ra0 ra0 (a) char word[5] = "star" (b) Call reverse (word, 0, ) (c) Switch s ad r (d) Call reverse (word,, 2)

54 Figure 2.4 2

55 Figure (a) Move three disks from peg to peg 2. (b) Move oe disk from peg to peg. (c) Move three disks from peg 2 to peg.

56 Figure (a) Move two disks from peg to peg. (b) Move oe disk from peg to peg 2. (c) Move two disks from peg to peg 2.

57 Figure 2.7

58 The C memory model Global variables fixed locatio i memory Local variables ad parameters ru-time stack Dyamically allocated variables heap

59 Two operators for dyamic memory allocatio malloc(), to allocate from the heap free(), to deallocate from the heap

60 Two actios of the malloc() fuctio It allocates a memory cell from the heap large eough to hold a value of the type that is o its right-had side. It returs a poiter to the ewly allocated storage.

61 The poiter assigmet rule If p ad q are poiters, the assigmet p = q makes p poit to the same cell to which q poits.

62 Figure 2.8 #iclude <stdio.h> #iclude <stdlib.h> it *a, *b, *c; it mai() { a = (it *) malloc(sizeof(it)); *a = 5; b = (it *) malloc(sizeof(it)); *b = ; c = a; a = b; *a = 2 + *c; pritf("*a = %d\", *a); pritf("*b = %d\", *b); pritf("*c = %d\", *c); retur 0; Output *a = 7 *b = 7 *c = 5

63 Figure 2.9 a a a 5 a 5 b b b b c c c c (a) Iitial state (b) a =... malloc(...) (c) *a = 5 (d) b =... malloc(...) a b c 5 a 5 a 5 a 5 b b b 7 c c c (e) *b = (f) c = a (g) a = b (h) *a = 2 + *c

64 Figure 2.40 #iclude <stdio.h> struct perso { char first; char last; it age; char geder; ; struct perso bill; it mai() { scaf("%c%c%d %c", &bill.first, &bill.last, &bill.age, &bill.geder); pritf("iitials: %c%c\", bill.first, bill.last); pritf("age: %d\", bill.age); pritf("geder: "); if (bill.geder == 'm') { pritf("male\"); else { pritf("female\"); retur 0;

65 Figure 2.40 (cotiued) Iput bj 2 m Output Iitials: bj Age: 2 Geder: male

66 Figure 2.4 #iclude <stdio.h> #iclude <stdlib.h> struct ode { it data; struct ode *ext; ; it mai() { struct ode *first, *p; it value; first = 0; scaf("%d", &value); while (value!= -9999) { p = first; first = (struct ode *) malloc(sizeof(struct ode)); first->data = value; first->ext = p; scaf("%d", &value); for (p = first; p!= 0; p = p->ext) { pritf("%d ", p->data); retur 0;

67 Figure 2.4 (cotiued) Iput Output

68 Figure 2.42 value value value 0 p p p first first first (a) Iitial state i mai() (b) first = 0 (c) scaf("%d", &value) value 0 value 0 value 0 p p p first first first 0 (d) p = first (e) first = malloc( ) (f) first->data = value value 0 value 20 value 20 p first p p 0 first 0 first 0 (g) first->ext = p (h) scaf("%d", &value) (i) p = first

69 Figure 2.42 (cotiued) value 20 value 20 p first p 0 first 20 0 (j) first = malloc( ) (k) first->data = value value 20 value 0 p p first 20 0 first 20 0 (l) first->ext = p (m) scaf("%d", &value)