3
CC
3.1 —— printf()
3.2 —— scanf()
3.3 —— getchar()putchar()
3.4
──
[Return]
3.1 —— printf()
printf()
3.1.1 printf()
[3.1] radius=1.5
/*AL3_1.C*/
main()
{float radius,length,area,pi=3.1415926;
radius=1.5;
length=2*pi*radius; /**/
area=pi*radius*radius; /**/
printf(“radius=%f\n”,radius); /**/
printf(“length=%7.2f,area=%7.2f\n”,length,area); /**/
}
[]
radius=1.500000
length= 9.42,area= 7.07
printf()
printf("" [])
1
1
%[][][.][F|N|h|L][]
3-13-23-33-43-5
2
[3.1]printf()'\n'
3──
[ 3.1] printf("radius=%f\n",radius);” radius=”
printf("length=%7.2f,area=%7.2f\n",length,area);” length=” area=”
2
12printf()
1printf("I am a student.\n");
2printf("%d",3+2);
3printf("a=%f b=%5d\n",a,a+3);
3.1.2
1 d──
[3.2] d
/*AL3_2.C*/
main()
{int num1=123;
long num2=123456;
/*3intnum1*/
printf("num1=%d,num1=%5d,num1=%-5d,num1=%2d\n",
num1,num1,num1,num1);
/*3longnum2*/
printf("num2=%ld,num2=%8ld,num2=%5ld\n",num2,num2,num2);
printf("num1=%ld\n",num1);
} []
num1=123,num1= 123,num1=123,num1=123
num2=123456,num2= 123456,num2=123456
num1=16908411
%o(o)%xunsigned %u
printf("%d,%o,%x\n",-1,-1,-1);
2 f──
[3.3] f
/*AL3_3.C*/
main( )
{float f=123.456;
double d1,d2;
d1=1111111111111.111111111;
d2=2222222222222.222222222;
printf("%f,%12f,%12.2f,%-12.2f,%.2f\n",f,f,f,f,f);
printf("d1+d2=%f\n",d1+d2);
} []
123.456001,123.456001,123.46,123.46,123.46
d1+d2=3333333333333.333010
123.4560013333333333333.333010001010
%e11054e-03e211
%g%f%e
3 c──
[3.4] c
/*AL3_4.C*/
main()
{char c='A';
int i=65;
printf("c=%c,%5c,%d\n",c,c,c);
printf("i=%d,%c",i,i);
}
c=A,A,65
i=65,A []
C256ASCII
4 s──
[3.5] s
/*AL3_10.C*/
main()
{printf("%s,%5s,%-10s","Internet","Internet","Internet");
printf("%10.5s,%-10.5s,%4.5s\n","Internet","Internet","Internet");
} []
Internet,Internet,Internet,Inter,Inter,Inter
3.1.3
1printf()
printf("str=%s,f=%d,i=%f\n","Internet",1.0 / 2.0,3 + 5,"CHINA");
2xegxeg
%f%F
3 %”
printf(”c=%c,f=%f\n“,c,f);”cf
[Return]
3.2 —— scanf()
scanf()
3.2.1 scanf()
[3.6] radius=1.5high=2.0
/*AL3_6.C*/
main()
{ float radius=1.5,high=2.0,pi=3.14159,vol;
vol=pi*radius*radius*high; /**/
printf(“vol=%7.2f\n”,vol); /**/
} []
[3.7] radiushigh
/*AL3_7.C*/
/*scanf()*/
main()
{float radius,high,vol,pi=3.1415926;
printf("Please input radius & high,");
scanf("%f%f",&radius,&high); /*r,h*/
vol=pi*radius*radius*high;
printf("radius=%7.2f,high=%7.2f,vol=%7.2f\n",
radius,high,vol);
} []
Please input radius & high,1.5 2.0
radius= 1.50,high= 2.00,vol= 14.14
Cscanf()
1,scanf()
scanf("",);
13Tab
printf()2
2──2
&
&”[3.7] &radius”radius
2 scanf()
[3.7]2&radius&highradiushigh
3.2.2
% [*] [] [F|N] [h|l]
1
3-6[3.7]scanf() %f%f”
2n
n
n
scanf("%3c%3c",&ch1,&ch2);
printf("ch1=%c,ch2=%c\n",ch1,ch2);
abcdefg” abc” a” ch1 def” d” ch2 printf()
ch1=a,ch2=d
3 *
scanf("%2d%*2d%3d",&num1,&num2);
printf("num1=%d,num2=%d\n",num1,num2);
123456789” 12” num1 34” * 567” num2
printf()num1=12,num2=567
4 ──F N h l
printf()
3.2.3
122Tab11
scanf("%d%d",&num1,&num2);
num1 12num23612 36
12
36
2
scanf("%d,%d",&num1,&num2);
num1 12num2361236
scanf()(\n)
scanf("num1=%d,num2=%d\n",&num1,&num2);
num112num236
num1=12 num2=36\n
printf()scanf()
scanf("num1=%d,num2=%d\n",&num1,&num2
);
printf("num1="); scanf("%d",&num1);
printf("num2="); scanf("%d",&num2);
3
1Tab
2 %3d”3
3(0-9)
4 %c”
scanf("%c%c%c",&ch1,&ch2,&ch3);
printf("ch1=%c,ch2=%c,ch3=%c\n",ch1,ch2,ch3);
A B C 'A'ch1' 'ch2'B'ch3
[Return]
3.3 —— getchar()putchar()
3.3.1 ──putchar()
[3.8] putchar()
/*AL3_8.C*/
/*putchar()*/
#include "stdio.h" /**/
main()
{char ch1='N',ch2='E',ch3='W';
putchar(ch1); putchar(ch2); putchar(ch3); /**/
putchar('\n');
putchar(ch1); putchar('\n'); /*ch1*/
putchar('E'); putchar('\n'); /*'E'*/
putchar(ch3); putchar('\n');
} []
NEW
N
E
W
1putchar() putchar(ch);
ch
2putchar()
1putchar()printf()putchar()
2putchar()
#include "stdio.h"
stdio.h
3.3.2 ──getchar()
[3.9] getchar()
/*AL3_9.C*/
/*getchar()*/
#include "stdio.h" /**/
main()
{char ch;
printf("Please input two character,");
ch=getchar(); /*1ch */
putchar(ch);putchar('\n');
putchar(getchar()); /**/
putchar('\n');
} []
Please input two characters,ab
a
b
1 getchar()getchar();
2 getchar()scanf()getchar()
1getchar()
2getchar()
#include "stdio.h“
[Return]
3.4
[3.10]
/*AL3_10.C */
/**/
main()
{int num1,num2,num3,sum;
float aver;
printf("Please input three numbers:");
scanf("%d,%d,%d",&num1,&num2,&num3);/**/
sum=num1+num2+num3; /**/
aver=sum/3.0; /**/
printf("num1=%d,num2=%d,num3=%d\n",num1,num2,num3);
printf("sum=%d,aver=%7.2f\n",sum,aver);
} []
aver=sum/3.0;” 3.0” 3”
[3.11] ax2+bx+c=0abca≠0b2-4ac>0
/*AL3_11.C*/
/**/
#include "math.h" /*sqrt()math.h */
main()
{float a,b,c,disc,x1,x2;
printf("Input a,b,c,");
scanf("%f,%f,%f",&a,&b,&c); /**/
disc=b*b-4*a*c; /*disc*/
x1=(-b+sqrt(disc))/(2*a);
x2=(-b-sqrt(disc))/(2*a);
printf("\nx1=%6.2f\nx2=%6.2f\n",x1,x2);
} []
[3.12] ASCII
/*AL3_12.C*/
#include "stdio.h"
main()
{char c1,c2;
printf("Input a lowercase letter,");
c1=getchar();
putchar(c1);printf(",%d\n",c1);
c2=c1-32; /**/
printf("%c,%d\n",c2,c2);
} []
Input a lowercase letter,a
a,97
A,65
1
printf()scanf()
2
1
2
3
4
[Return]
──
[Return]