C primer plus第5章（运算符、表达式和语句）习题

3.

#include <stdio.h>
int main (void)
{
int i = 1;
float n;
printf("Watch out! Here come a bunch of fractions!\n");
while(i++ < 30) {
n = 1.0/i;//将1改为1.0，当2个数都是整数时，第一次结果为1，当I增大时结果会一直为0，改为1.0（浮点型）则会有不同结果
printf("%f\n",n);
}
printf("That`s all,folks!\r");
return 0;
}

4.

#include <stdio.h>
#define FORMAT "%s! C is cool!\n"
int main (void)
{
int num = 10;
printf(FORMAT, FORMAT);
printf("%d\n", ++num);
printf("%d\n", num++);
printf("%d\n", num--);
printf("%d\n", num);
return 0;
}

结果

%s! C is cool!

! C is cool!

11

11

12

11

6.

#include <stdio.h>
int main (void)
{
char c1,c2;
int diff;
float num;

c1 = 'S';
c2 = 'O';
diff = c1 - c2;
num = diff;
printf("%c%c%c: %d %3.2f\n", c1, c2,c1,diff,num);
return 0;
}

打印结果

SOS: 4 4.00

7.

#include <stdio.h>
#define TEN 10
int main (void)
{
int n = 0;
while(n++ < TEN)
printf("%5d",n);
printf("\n");
return 0;
}

8.

#include <stdio.h>
int main (void)
{
char c = 'a';
while(c <= 'g')
printf("%5c",c++);
printf("\n");
return 0;
}

9.

a.

1 2

b.

101

102

103

103

c.

stuvw

编程练习

1.

#include <stdio.h>
int main (void)
{
const int MAX = 60;
int num;
while(num > 0) {
scanf("%d",&num);
}
return 0;
}

2.

#include <stdio.h>
int main (void)
{
int pl = 10;
int num;
printf("请输入数字\n");
scanf("%d",&num);
while(pl >= 0) {
printf("%d\n",num+pl);
pl--;
}
return 0;
}

3.

#include <stdio.h>
int main (void)
{
const int PW = 7;
int days;
printf("请输入天数\n");
scanf("%d",&days);
printf("%d周%d天",days/PW,days%PW);
return 0;
}

4.

#include <stdio.h>
int main (void)
{
const float I_T_M = 2.54;
const float M_T_I = 0.3937;
float cm;
while(cm > 0) {
printf("请输入厘米长度\n");
scanf("%f",&cm);
printf("%.2fcm\n%.2finch\n",cm,cm*I_T_M);
}
return 0;
}

5.

#include <stdio.h>
int main (void)
{
int count,sum,days;
count = 0;
sum = 0;
scanf("%d",&days);
while(count++ < days)
sum = sum + count;
printf("sum = %d\n", sum);
return 0;
}

6.

#include <stdio.h>
int main (void)
{
int count,sum,days;
count = 0;
sum = 0;
scanf("%d",&days);
while(count++ < days)
sum = sum + count * count;
printf("sum = %d\n", sum);
return 0;
}

7.

#include <stdio.h>
int main (void)
{
float num;
scanf("%f",&num);
printf("%f", num * num * num);
return 0;
}

8.

#include <stdio.h>
//用到atof函数需要此包
#include <stdlib.h>
int main (void)
{
char fahrenheit[40];
double params;
int n;
while(1)
{
printf("请输入华氏温度\n");
scanf("%s",fahrenheit);
n = strlen(fahrenheit);
int i = 0;
for(i=0; i<n; i++)
{
if((fahrenheit[i] < '0' || fahrenheit[i] > '9') && fahrenheit[i] != '.')
{
return 0;
}
}
temperatures(atof(fahrenheit));
}
return 0;
}

void temperatures(double fahrenheit)
{
const float C1 = 1.8;
const float C2 = 32.0;
const float K = 273.16;
double celsius,kelvin;
celsius = C1 * fahrenheit + C2;
kelvin = celsius * K;
printf("摄氏%f度\n",celsius);
printf("绝对温度%f度\n",kelvin);
}