4.8编程练习
2
/* 4.8.2.c -- 打印名字 */
#include <stdio.h>
int main()
{
printf("Please enter your name: ");
char name[20];
scanf("%s", name);
printf("\"%s\"\n", name);
printf("\"%20s\"\n", name);
printf("\"%-20s\"\n", name);
printf("%*s\n", strlen(name) + 3, name);
return 0;
}
4
/* 4.8.4.c -- 输出身高和姓名信息。 */
#include <stdio.h>
int main()
{
float height;
char name[20];
printf("Please enter your height in feet: ");
scanf("%f", &height);
printf("Please enter your name: ");
scanf("%s", name);
printf("%s, you are %.3f feet tall.", name, height);
return 0;
}
6
/* 4.8.6.c -- 打印姓名及长度。 */
#include <stdio.h>
#include <string.h>
int main()
{
char first[20], last[20];
printf("Please enter your firstname: ");
scanf("%s", first);
printf("Please enter your lastname: ");
scanf("%s", last);
int flen = strlen(first);
int llen = strlen(last);
printf("%s %s\n", first, last);
printf("%*d %*d", flen, flen, llen, llen);
printf("\n");
printf("%s %s\n", first, last);
printf("%-*d %-*d", flen, flen, llen, llen);
return 0;
}
8
/* 4.8.6.c -- 旅行里程和耗油量。 */
#include <stdio.h>
#define LITRE_PER_GALLON 3.785
#define KM_PER_MILE 1.609
int main()
{
double mile, gas;
printf("Please enter your trip distance in mile: ");
scanf("%lf", &mile);
printf("Please enter the gas you consumed in gallon: ");
scanf("%lf", &gas);
double milePerGallon = mile / gas;
printf("The distance per gallon of gas is %.1f miles.\n", milePerGallon);
printf("convert to litre per one hundred km: %.1f\n", 1 / milePerGallon / LITRE_PER_GALLON * KM_PER_MILE / 100);
return 0;
}
5.11编程练习
1
/* 5.11.1.c -- 把分钟显示成“小时+分钟”，直到用户输入小于等于零的时间 */
#include <stdio.h>
#define MIN_PER_HOUR 60
int main()
{
int minutes;
do
{
printf("Please enter minutes: ");
scanf("%d", &minutes);
if (minutes > 0)
{
int h = minutes / MIN_PER_HOUR;
int m = minutes % MIN_PER_HOUR;
printf("It's %02d:%02d.\n", h, m);
}
else
break;
}
while(1);
return 0;
}
2
/* 5.11.2.c -- 打印从某个数到比他大10的所有整数。 */
#include <stdio.h>
int main()
{
int num;
printf("Please enter an integer: ");
scanf("%d", &num);
for (int current = num; current <= num +10; current++)
{
printf("%d\n", current);
}
return 0;
}
3
/* 5.11.3.c -- 将天数显示成“周数+天数” */
#include <stdio.h>
int main()
{
int days;
while (1)
{
printf("Please enter the number of days: ");
scanf("%d", &days);
if (days <= 0)
break;
int w = days / 7;
int d = days % 7;
printf("%d days are %d weks, %d days.\n", days, w, d);
}
return 0;
}
4
/* 5.11.4.c -- 重复接收身高并改单位输出。 */
#include <stdio.h>
int main()
{
/* 一厘米等于0.3937英寸，一英尺等于12英寸。 */
double centi;
while (1)
{
printf("Enter a height in centimeters: ");
scanf("%lf", ¢i);
if(centi <= 0)
break;
double inches = centi * 0.3937;
int f = ((int)inches) / 12;
double i = inches - f * 12;
printf("%.1f cm = %d feet, %.1f inches\n", centi, f, i);
}
return 0;
}
5
/* 5.11.5.c -- 前n个整数累加 */
#include <stdio.h>
int main()
{
int current, sum, max;
printf("Please enter a number: ");
scanf("%d", &max);
current = 0;
sum = 0;
while (current++ < max)
sum += current;
printf("sum = %d\n", sum);
return 0;
}
6
/* 5.11.6.c -- 前n个整数平方和 */
#include <stdio.h>
int main()
{
int current, sum, max;
printf("Please enter a number: ");
scanf("%d", &max);
current = 0;
sum = 0;
while (current++ < max)
sum += (current * current);
printf("sum = %d\n", sum);
return 0;
}
7
/* 5.11.7.c -- 立方 */
#include <stdio.h>
double cube(double value)
{
return value * value * value;
}
int main()
{
double num;
printf("Enter a double number: ");
scanf("%lf", &num);
printf("It's cube is: %.2f", cube(num));
return 0;
}
8
/* 5.11.8.c -- 求模运算 */
#include <stdio.h>
int main()
{
int first, second;
printf("This program computes moduli.\n");
while (1)
{
printf("Enter an integer to serve as the second operand: ");
scanf("%d", &second);
printf("Now enter the first operand: ");
scanf("%d", &first);
if (first <= 0 || second <= 0)
break;
printf("%d %% %d is %d\n", first, second, first % second);
}
return 0;
}
9
/* 5.11.9.c -- 温标换算 */
#include <stdio.h>
void Temperatures(double fa)
{
const double absZero = 273.16;
double centigrade = 5.0 / 9.0 * (fa - 32.0);
printf("in centigrade is: %.2f\n", centigrade);
printf("in kelvin is: %.2f\n", centigrade + absZero);
}
int main()
{
double fahrenheit;
while (1)
{
printf("Enter a fahrenheit dregree: ");
if (scanf("%lf", &fahrenheit))
Temperatures(fahrenheit);
else
break;
}
return 0;
}
总结&感悟
- Q：如何动态地指定打印宽度？平常指定一个固定宽度写法：
printf("%5d", num)（右对齐、宽度5、打印十进制数），如果5不能在编译时知道，怎么办？
A: printf("%*d", length, num)：用*代替具体宽度，后面参数加一个长度length。
