C++ premier plus 第六版 編程練習解答（第三章）

1.編寫一個小程序，要求用戶使用一個整數指出自己的身高，然後將身高轉換爲英尺和英寸。該程序使用下劃線字符來指示輸入位置。另外，使用一個const符號常量來表示轉換因子。

#include<iostream>
int main()
{
	using namespace std;
	const float Rate = 12.0;
	int inch;
	float feet;
	cout << "您的身高爲____英寸\b\b\b\b\b\b\b\b";
	cin >> inch;
	feet=(float) inch / Rate;
	cout << "您的身高爲 " << feet << " 英尺" << endl;
	return 0;
}

2.編寫一個小程序，要求以幾英尺幾英寸的方式輸入其身高，並以磅爲單位輸入其體重。（使用3個變量來存儲這些信息。）該程序報告其BMI（Body Mass Index，體重指數）。

#include<iostream>
int main()
{
	using namespace std;

	const float RateA = 12.0;
	const float RateB = 0.0254;
	const float RateC = 2.2;
	float feet,inch,meter,pound,kg,bmi;

	//輸入部分
	cout << "請您按英尺、英寸、磅的順序輸入身高體重：" << endl;
	cout << "英尺： ";
	cin >> feet ;
	cout << "英寸： ";
	cin >> inch;
	cout << "磅： ";
	cin >> pound;

	//計算部分
	inch = inch + feet * RateA;
	meter = inch * RateB;
	kg = pound * RateC;
	bmi = meter * meter / kg;

	//顯示部分
	cout << "你的BMI指數爲： " << bmi << endl;

	return 0;
}

3.編寫一個程序，要求用戶以度、分、秒的方式輸入一個緯度，然後以度爲單位顯示該緯度。

#include<iostream>
int main()
{
	using namespace std;
	const float Rate = 60.0;
	float degree,minute,second,final;

	//輸入部分
	cout << "Enter a latitude in degrees, minutes, and seconds :" << endl << "First, enter the degrees: ";
	cin >> degree;
	cout << "Next, enter the minutes of arc: ";
	cin >> minute;
	cout << "Finally, enter the seconds of arc: ";
	cin >> second;

	//計算部分
	final = (float) degree + minute / Rate + second /Rate / Rate;

	//輸出部分
	cout << degree << " degrees, " << minute << " minutes, " << second << " second = " << final << " degrees" << endl;

	return 0;
}

4.編寫一個程序，要求用戶以整數方式輸入秒數，然後以天、小時、分鐘和秒的方式顯示這段時間。

#include<iostream>
int main()
{
	using namespace std;
	long second,seconds;
	int days,hours,minutes;
	cout << "Enter the number of seconds: ";
	cin >> second;
	seconds = second;
	days = seconds / ( 60*60*24 );
	seconds = seconds % ( 60*60*24 );
	hours = seconds / 3600;
	seconds = seconds % 3600;
	minutes = seconds / 60;
	seconds = seconds % 60;
	cout << second << " seconds = " << days << " days, " << hours << " hours, " << minutes << " minutes, " << seconds << " seconds" << endl;
	return 0;
}

5.編寫一個程序，要求用戶輸入全球當前的人口和美國當前的人口。將這些信息儲存在long long 變量中，並讓程序顯示美國的人口占全球人口的百分比。

#include<iostream>
int main()
{
	using namespace std;
	long long world,us;
	float rate;
	cout << "Enter the world's population: ";
	cin >> world;
	cout << "Enter the population of the US: ";
	cin >> us;
	rate = (float) us / world * 100;
	cout << "The population of the US is " << rate << "% of  the world population" << endl;
	return 0;
}

6.編寫一個程序，要求用戶輸入驅車裏程（英里）和使用汽油量（加侖），然後指出汽車耗油量爲一加侖的里程。

#include<iostream>
int main()
{
	using namespace std;
	float distance,gasoline,result;
	cout << "Enter the distance: ";
	cin >> distance;
	cout << "Enter the gasoline consumption: ";
	cin >> gasoline;
	result = (float) distance / gasoline;
	cout << "The car can run " << result << " miles with 1 gallon gasoline." << endl;
	return 0;
}

7.編寫一個程序，要求用戶按歐洲風格輸入汽車的耗油量（每100公里消耗的汽油量（升）），然後將其轉換爲美國風格的耗油量（每加侖多少英里）。

#include<iostream>
int main()
{
	using namespace std;
	float us,eu;
	cout << "Please input the fuel consumption according to the European style:" << endl << "Fuel consumption is:____/100km\b\b\b\b\b\b\b\b\b\b";
	cin >> eu;
	us = (float) 62.4 / eu * 3.875;
	cout << "The fuel consumption converted to American style is: " << us << "mpg" << endl;
	return 0;
}