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1 #"$)(+-,#.)/ :1; <-:1; = >? B C DFEG H IJ K# L M#N " # $ " $ ( ) (+, -. / / $ (0. # 1 2 ( # " 3 4 DFEG H IJPOQ I R TS U VEW G # / / 3 (4 $ 5 # # $ - ) $ 3 : ;, ; + 3 < 3 ( ( < = 8 9 #, < 1 < $ 3 # 3 < 5 6 1

2 U VEW G EW G $ 3 $ >,?, > 3 $ 3 $ ) A # B 5 ; A $ / C ; C 9 " B : 3 < / / $ E $ 3 (6 7 D 9 E ( E(" / / 7 8 U S 7 9 C 9 5 : B E # ( F G" H ( / / I / / J F G 9 10 B T I I P I Q I H H $ ( : ( 3 < ( 3 (3 (0 ( ( / / ( (# = (, ( (; (0 K # 3 3 (I K # 3 E / (A A ( < S < ( <

3 S S / / E O P ( 9 ( ( L 9 M N S U java StartClass " StartClass.main I # J B main() B. ( " B.( S public class hello { public static void main (String args []) { System.out.println ( Hello world ); int main(int argc, char argv[]) { puts( Hello, World ); return 0; struct list{int data; struct list next; struct list start, end; void add(struct list head, struct list list, int data; int delete(struct list head, struct list tail); void main(void){ start=end=null; add(start, end, 2); add(start, end, 3); printf( First element: d, delete(start, end)); void add(struct list head, struct list tail, int data{ if(tail==null){ head=tail=malloc(sizeof(struct list)); head->data=data; head->next=null; else{ tail->next= malloc(sizeof(struct list)); tail=tail->next; tail->data=data; tail->next=null;

4 void delete (struct list head, struct list tail){ struct list temp; if(head==tail){ free(head); head=tail=null; else{ temp=head->next; free(head); head=temp; void main(void) { printf( Hello World. \n \t and you \n ); / print out a message / return; 19 $Hello World. and you $ 20 Q I E T U H TQ I E U stdio.h Q + 3 B void main(void){ printf( / message you want printed / ); \n A (\t A R printf. printf( Have you heard of \ The Rock\? \n ); int main(int argc, char argv[]) int 9 (> TQ I U TQ I U + / S. 6 T = U H argc 4 argv ( int main() { puts( Hello World ); exit(0); ) exit() B. a.out 1 23 third arg

5 TQ I U TQ I U (, ( (E B E foo.java foo.class I # " foo.c a.out a.out x.pl x.java x.c, x.cc perl javac gcc, g++ data args results java a.out E Q U.H QQ QQ ". F G $ gcc hello.c $ a.out Hello, World $ E B B I QQ U I IJQQ,? B. " gcc o hello hello.o 3 " gcc c a.c. gcc c b.c. gcc o hello a.o b.o ) gcc o calc calc.c -lm # "

6 U I IJQQ QQ gcc ( ( B gcc H B 5 if (x = 0).if (x == 0) E ) " undefined symbol first referenced in file _print program.o ld fatal: Symbol referencing errors No output written to file U U Q U U Q, 1 #define MAXVALUE 100 #define check(x) ((x) < MAXVALUE) if (check(i) { if ((i) < 100) { Q ( gcc E U U Q U U Q #define #define 6 ( T (0 #undef symbol 1 #define MAXLEN getchar(), putchar() H " #define valid(x) ((x) > 0 (x) < 20) if (valid(x++)) { valid(x++) -> ((x++) > 0 (x++) < 20)

7 U U Q - T.H I Q H B I #include filename.h #include <filename.h> F G L > /usr/include gcc I. 1 #include mydefs.h #include /home/alice/program/defs.h U U Q Q I L I H Q U.H I #if expression code segment 1 #else code segment 2 #endif " ( 6 ( T " B - #define OS linux #if OS == linux puts( Linux ); #else puts( Something else ); #endif U U Q VA T B Q IJU U Q : ( #ifdef name code segment 1 #else code segment 2 #endif " #define USEDB ( 6 ( T 3 Q +, 6 8 > Q # K > Q ( > > I (. (? I B QT G U / any text until / // / / B - / /( / / / AverageGrade() Given an array of grades, compute the average. / B ( ". (. 6 T V D V D 6 T D 0 6 T C 8 W W = W W = W "# $# "# $#

8 IJT G U ; B int F G 2 (..(8 V 8 V ( int A = T (long A 8 V (unsigned ( char A 6 F G ( void main(void) { int nstudents = 0; / Initialization, required / printf( How many students does Columbia have?: ); scanf ( d, nstudents); / Read input / printf( Columbia has d students.\n, nstudents); return ; $ How many students does Columbia have?: (enter) Columbia has students LG U Q I B I TU H Q I U H Q Q I B I void main(void) { int i,j = 12; / i not initialized, only j / float f1,f2 = 1.2; i = (int) f2; / explicit: i <- 1, 0.2 lost / f1 = i; / implicit: f1 <- 1.0 / f1 = f2 + (int) j; / explicit: f1 < / f1 = f2 + j; / implicit: f1 < /..(s = a (int) + b (char) char > short > int > 0 double( double float( float(. 1 B type B LG U Q I B I I H I int x = ; short s; s = x; printf( d d\n, x, s); = 6 9 C T H 1 ( if (n = 0) { printf( something wrong ); 2 >

9 VT T I G U T I I G C I H I typedef typedef short int smallnumber; typedef unsigned char byte; typedef char String[100]; smallnumber x; byte b; String name; typedef char boolean; #define FALSE 0 #define TRUE 1 " ( check = x > 0; if (check == TRUE) { x ( " 2 ( I G U I G U 5 " typedef enum { Red, Orange, Yellow, Green, Blue, Violet Color; enum weather {rain, snow=2, sun=4; " " " ( B color + weather H " typedef enum { Red, Orange, Yellow Color; " #define Red 0 #define Orange 1 #define Yellow 2 typedef enum {False, True boolean; 51 8Q K H Q 4BE M 8Q E / / I H short int x; char ch; float pi = ; float f, g; I M N " " I " ( I A ( ) B 2 ch = a ; x = x + 4; ( scanf( df, x, f);

10 8Q 8Q 1 E 2 int foo(char x) { return x; pt = foo(x); pt = 17; ) " ( E 2 E 2 E E E E " E QQ I 8QQ I int x; int arr[20]; int main(int argc, char argv[]) { int i = 20; {into x; x = i + 7; int f(int n) { int a, p; a = 1; p = (int )malloc(sizeof int); malloc() " 3 ( free(). # " B char combine(char s, char t) { u = (char )malloc(strlen(s) + strlen(t) + 1); if (s = t) { strcpy(u, s); strcat(u, t); return u; else { return 0; GJ H H Q I " " ( 2 + (. 59 G H G U Header info Code Data - Heap Data - stack 5 3 / " 60 10

11 8Q I U I 8Q I U I, E(..(int x x int, type V < D int, E(..(int x 2 2 size_t( int - 1, < / /, 4 4 E, Eint xp x( xp x( int xp x 42 int int x Q I U I U I E( 4 E 4 E " E int a, b, c, d; d = 17; / BAD idea / a = 2; b = 3; c = a; d = b; if (c == d) puts( Same value ); c = 3; if (c == d) puts( Now same value ); c = d; if (c == d) puts ( Now same address ); ) " ( " I H Q I Q I I U I J ; {... if(switch for(while 6 X T X X J M...N " M N M N J " E "

12 4E I if 4E I if if (condition 1 ) {statements 1 else if (condition 2 ) {statements 2 else if (condition n-1 ) {statements n-1 else {statements n 2 M N ( if (x > 0) printf( x > 0 ); if (y > 0) printf( x and y > 0 ); E I switch 4E I switch switch(expression) { case const1: statements1; break; case const2: statements2; break; default: statementsn; 1 " Weather w; switch(w) { case rain: printf( bring umbrella ); case snow: printf( wear jacket ); break; case sun: printf( wear sunscreen ); break; default: printf( strange weather ); U I 4E I break M N M...N XX 2 ( 9 ( 9 2 ( 2 " for (init; condition; next) { statements1; if (condition2) break; statements2;

13 4E I continue Q T 8 Q continue " ( next for (init; condition1; next) { statement2; if (condition2) continue; statement2; if " E E array [] struct union ( G G int vec[100]; char str[30]; float m[10][10]; : + ( ( int x[10]; x[10] = 5; " " sizeof A sizeof A /sizeof A[0] 2 2 PrintArray(A, VECSIZE); struct ( ( E" #define VECSIZE G G O P 1 int i, sum = 0;... for (i = 0; i < VECSIZE; i++) sum += vec[i]; "..( " vec[-1] vec[10000] - H " ( Segmentation fault (core dumped) array J? O9 P int v, last; int sum = 0; last = vec[vecsize-1]; for (v = vec; v <= last; v++) sum += v;

14 V G G V T U H T int weekends[52][2]; [0][0] [0][1] [1][0] [1][1] [2][0] [2][1] [3][0].... weekends void main(void) { int number[12]; / 12 cells, one cell per student / int index, sum = 0; / Always initialize array before use / for (index = 0; index < 12; index++) { number[index] = index; / now, number[index]=index; will cause error:why?/ for (index = 0; index < 12; index = index + 1) { sum += number[index]; / sum array elements / return; weekends[2][1] (weekends+22+1) +, weekends B T O : H + 4 " # $ # ( ) ) B I I Q I I Q I U I ( (, (T (... X (4 X Q Q E<. 1 struct {int x; char y; float z; rec;... r.x = 3; r.y = a ; r.z= ; ; 1 struct complex {double real; double imag;; struct point {double x; double y; corner; typedef struct {double real; double imag; Complex; struct complex a, b; Complex c,d; a b 2 ( a c 2 (

15 Q Q V T U H 2 ( struct { char x; int y; char z; s1; sizeof(s1) =? struct { char x, z; int y; s2; sizeof(s2) =? struct person { char name[41]; int age; float height; struct { / embedded structure / int month; int day; int year; birth; ; struct person me; me.birth.year=1977; struct person class[60]; / array of info about everyone in class / class[0].name= Gun ; class[0].birth.year=1971; Q I Q I U I Q H I (..( typedef struct { unsigned int version:2; unsigned int p:1; unsigned int cc:4; unsigned int m:1; unsigned int pt:7; u_int16 seq; u_int32 ts; rtp_hdr_t; H +, - + H ". +, T H I I ( 2..( C (..( < B (x 0x8000) >> 31 3 " union u_tag { int ival; float fval; char sval; u;

16 U I I Q I V C EGJ I E C N int month[12]; / month is a pointer to base address 430/ month[3] = 7; / month address + 3 int elements => int at address (430+34) is now 7 / ptr = month + 2; / ptr points to month[2], => ptr is now (430+2 int elements)= 438 / ptr[5] = 12; / ptr address + 5 int elements => int at address (434+54) is now 12. Thus, month[7] is now 12 / ptr++; / ptr < size of int = 442 / (ptr + 4)[2] = 12; / accessing ptr[6] i.e., array[9] / + ( month[6], (month+6), (month+4)[2], ptr[3], (ptr+3). # 2 B Y Y $ $ ; $ $ I Q I I Q I. extern int putchar(int c); putchar( A ); int putchar(int c) { do something interesting here (, (. L. > static int x; static int times2(int c) { return c2; I Q I Q I I H. " / 0 ) ( 1 2 # 3 # / 0 ) ( 1. I Q I V extern char user2line [20]; / global variable defined in another file / char user1line[30]; / global for this file / void dummy(void); void main(void) { char user1line[20]; / different from earlier user1line[30] /... / restricted to this func / void dummy(){ extern char user1line[]; / the global user1line[30] /

17 @A BH I I Q I S H BH I I Q I $ $ - - H ( $ $ $ " L. > $ $ " $ $ 2 2 $ " $, 6 + H " (, BH I I Q I C EA H U H T.H 3 " #include mypgm.h void main(void) { myproc(); 7 #include mypgm.h void myproc(void) { mydata=2;... / some code / ) void myproc(void); int mydata; EW I IJ I J I Q I H ( 8 ( 1 ( : 5 - : " : : : : 7 8 " : Z 8 ( 1 ( : : : 7 8 int func(); /function returning integer/ int func(); /function returning pointer to integer/ int (func)(); /pointer to function returning integer/ int (func)(); /pointer to func returning ptr to int/

18 $ $ I Q IJU I $ ; < < 103 I J I Q IJV T U H void myproc (int d); void mycaller(void ( f)(int), int param); void main(void) { myproc(10); / call myproc with parameter 10/ mycaller(myproc, 10); / and do the same again / void mycaller(void ( f)(int), int param){ (f)(param); / call function f with param / void myproc (int d){... / do something with d / 104 B 4E E H G < -. : = - > > )? :,? 7 = :, 7 = E Q B I, D..(UHA 8 W (U$ HA 8 8 (... ( " - O 2 [ 9 7 P 7 O 2 [ P O 9 7 P O \ -] Q ^ _?...P O R R P O [ P O 2 P 107 ( E ( E ( 2 A F G A a c a t \0 F G R9 H

19 B I B I char makebig(char s) { s[0] = toupper(s[0]); return s; makebig( a cat ); char str = my string ; char s; s = str[0]; s = str; " R9 char str = my string ;... int i; for (i = 0; str[i] = \0 ; i++) putchar(str[i]); char s; for (s = str; s; s++) putchar(s); B I UG I B I " B 2 2 C D D B C " B C. s = t B s t ( X char mybuffer[100];... mybuffer = a cat ; " - ) strcpy(mybuffer, a cat ) T U H B I I U H I B I S E H G #include <string.h> int main(void) { char line[100]; char family, given, gap; printf( Enter your name: ); fgets(line,100,stdin); given = line; for (gap = line; gap; gap++) if (isspace(gap)) break; gap = \0 ; family = gap+1; printf( Your name: s, s\n, family, given); return 0; ( ) - + ) 3 - X + ) 3 X + )

20 B I S E H G B I ( + ) 3 X + ) 3 < = (V (W (... $ = (V (W ( B I B I,,, " " : B E C B I B I V T U H : I E X E nc nd n.mf ( ( ( 4 F = ; G 5 B 2 C B 2 C $ D D $ D n.mg n.ms ( ( H 4 5 I $

21 4E H G " FILE E FILE stdin( stdout( stderr H O H M 4E G UI K#M Q K : J K ) 1 FG (F G (FG (F/ G? : (+ ) 3 3 J K ) 1 : (1 : Q E JH X 1 L J J K ) 1 : 3 1 X 1 L J X 1 L J J K ) 1 X 1 L J $ J K ) 1 A 2 6 URH ( " (+ ) 3 3 B J K ) 1 2 A 1 : 123 G S J K ) 1 J K ) 1 ( J (( H 5 H H + B " # H ( ( (