4 C --4.1 C 4.2 4.3 4.4 4.5 4.6

4.1 C Cint a;

C

1.2.3.4.5.

AP

2000-2050leap year,4100100400Y 2000Y/40YNyY/1000yY/4000yyy+1 yY>2500

4.2 = x=x+1 a = 1 a = = 1 a=2x=b 2=a b=x if x > 0 t = a; if (a = b) > 0 t = a; if (a = b ;) > 0 t = a;

4.3 C

C ,printfscanfC sizeof a=sizeof(int) #include stdio.h #include math.h #include string.hprintfscanf

4.44.4.1 putchar( putcharcc c #include stdio.h main ( ) { char a ,b ,c ; a =B ; b =O ; c =Y ; putchar(a) ; putchar(b) ; putchar( c);}:BOY: putchar(a) ; putchar(\n) ; putchar(b); putchar(\n) ; putchar(c) ; putchar (\n);}?

putchar(\101) putchar(A),putchar(65);putchar(\) putchar(\015 putchar(\r)

4.4.2 getchar()( getchar() 4.2 #include main(){char c;c=getchar();putchar(c); }aaputchar (getchar());printf(%c, getchar());#include getchar()

4.5 4.5.1 printf formatprintf()1. printf

printf%d%dab printfa=%d b=%dab a=3 b=4

2. 1. d%d printf%d%dab%md printf%4d%4dab a=123; b=12345; printf(%4d,%4d,a,b); 123,12345%ld printf%ld%ldab printf (%10ld),a) ; a=1234 1234 2. o8%o %mo%lo int a = -1 printf%d%oaa- 1 177777

3. x16%x %mx %lx printf%d%o%xaaa - 1 177777ffff00xprintf%d0%o0x%xaaa - 1 01777770xffff

4. u. main {unsigned int a = 65535 int b = -2 printfa=%d%o%x%u\n,a,a,a,a); printfb=%d%o%x%u\n,b,b,b,b);}a= -1177777ffff65535 b= -2177776fffe65534

int -32768~+32767 unsigned 0~65535intshort 2Blong 4B

5. cmain {char a =aint b = 97 print%c%d\naa print%c%dbb}a97 a970~255 printf%3dc

6. s% s % ms mm% -ms mm% m.ns mn% -m.ns nmmain {printf%3S%7.2s% .4s% -5.3\nCHINACHINACHINACHINA}CHINACHCHINCHI

7. f%f67166main {float xyx=111111.111y=222222.222 printf%fx+y}333333.326125main {double xyx=1111111111111.111111111 y=2222222222222.222222222 printf%fx+y}3333333333333.333010

% m.nf mn% -m.nf main { float f=123.456 printf%f %12f %12.2f % -12.2f %.2f \n, f,f,f,f;}:123.455994123.455994123.46 123.46123.46

8. e% e ,6,5e.: printf(%e,%e,123.456,0.006543); :1.234560e+002,6.543000e-003% m.ne% -m.ne m- , n.: float f = 123.456; printf(% e,%10e,%10.2e,% .2e,% -10.2e,f,f,f,f,f);:1.234560e+002,1.234560e+002,1.23e+002, 1.23e+002,1.23e+002

9. g%f%efloat f = 123.456 printf%f%e%gfff:123.456000,1.234560e+002,123.456

printf,: X,E,G dDdoxucsfeg% printf(c=%cf=%fs=%s,c,f,s):%% printf%f % %1.0/3 0.333333%

4.5.2 scanf scanf,:scanf (,): main ( ) { int a,b,c; scanf(%d%d%d,&a,&b,&c); printf(%d,%d,%d\n,a,b,c);}:345 3453 3(Tab)4 45 5:3 , 4 , 5

385abc1cf41cf61cf8

scanf:1. printf,%u%g2.,,: scanf(%3d%3d,&a,&b); :1234563. %,,:scanf(%2d%*3d%2d,&a,&b); :12345674.,: scanf(%7.2f,&a);.

scanf:1.,scanf(%d,%d,a,b); 2.,,:scanf(%d : %d : %d, &a , &b ,&c);scanf(a=%d , b=%d , c=%d, &a , &b ,&c);3.%c,,:scanf(%c %c %c, &a , &b ,&c);:a b c4.,,scanf(%d%c%f,&a,&b,&c);1234a1230.26

4.64.10 s=(a+b+c)/2

#include math.hmain(){float a,b,c,s,area; scanf(%f,%f,%f,&a,&b,&c);s=1.0/2*(a+b+c); area=sqrt(s*(s-a)*(s-b)*(s-c));printf(a=%7.2f,b=%7.2f,c=%7.2f\n,a,b,c);printf(s=%7.2f,area=%7.2f\n,s,area);}: 3,4,6a=3.00,b=4.00,c=6.00s=6.50,area=5.33

2:#include stdio.hmain(){char c1 ,c2 ;c1 = getchar();printf(%c,%d\n, c1 ,c1);c2 = c1+32;printf(%c,%d\n,c2 ,c2);}:A A,65 a,97

#include stdio.hmain(){char c1 ,c2 ,c3,c4;c1 = getchar();c3 = getchar();printf(%c,%d\n, c1 ,c1);printf(%c,%d\n, c3 ,c4);c2 = c1+32;c4 = c4+32;printf(%c,%d\n,c2 ,c2);printf(%c,%d\n,c4 ,c4);}AB

printfscanf

,,91.if ( ) ~ else ~2.for ( ) ~3.while ( ) ~4.do ~ while ( )5.continue6.break7.switch8.goto9.returnswitch: if (x > y) z = xelse z = y while ( i

printf (This is a C program!) scanf(%d, &a) putchar(a) max( ) max (2 , 5) x = max (2 , 5)

a = 3 a = 3 : i = i + 1 i = i + 1 n + + n + + x + y x + y () z = max (2 5) z = max (2 5) C , C .

, if ( x > = 0) else y = x while x = = 1

{ } if (x > 0) {i+ +sum = sum + x } else { j+ +sub = sub + x}while x= = 1i+ +a = b + c while x= = 1{i+ +a = b + c }

AB1int x yzx = 2y = 3z = x+y;2main {int abcd a = 8b = 9 c = + +ad = + +b printf%d%d%d%d,a,b,c,d}

pabab if (x > y) z = xelse z = yif (x > 0) {i+ +sum = sum + x } else { j+ +sub = sub + x}

while I

#include stdio.hmain(){ char b; printf (Please enter a character:); b=getchar(); putchar (b); getchar();}

1. A) a=1,b=2 B) i++; c) a=b=5 d) y=int (x);2 . (1) A) \t B) \018 C) \n D) \xaa(2) A) \\ B) 101 C) \ D) \xaa(3) A) \t B) \011 C) \n D) \o17 3. 1 A) 0x16 B) 016 C) -16 D) 0xaaaa (2) A) oxcc B) -017 C) -0x12 D) 0xffff 4. 1 A) 0.0 B) 5L C) o13 D) 986l (2) A) 8.9e1.2 B) 1e1 C) 0xFF00 D) 0.825e2 (3) A) a B)\ C) 0xaa D) 50.

5. printf (%d\n, (int)(2.5+3.0)/3); A) B) 2 C) 1 D) 06.main() {int a=9; a+=a-=a+a; printf(%d\n,a);}A) 18 B) 9 C) -18 D) -97. #include main() { char c1,c2,c3,c4,c5,c6;scanf(%c%c%c%c, &c1, &c2, &c3, &c4);c5=getcahr(); c6=getchar(); putchar(c1); putchar(c2);printf (%c%c\n,c5,c6);} 123 45678 A) 1267 B) 1256 C) 1278 D) 1245