C++ Primer Plus 第六版编程练习——第2章

★★★★★备注★★★★★

使用的编译环境为 Visual Studio 2017   

默认省略了如下内容：                           

     #include "stdafx.h"                           
     #include <iostream>                               

     using namespace std;

1. Write a C++ program that displays your name and address (or if you value your privacy, a fictitious name and address).

int main(int argc, const char*[])
{
	cout << "My name is ××× and I live in ×××" << endl;
	return 0;
}

2. Write a C++ program that asks for a distance in furlongs and converts it to yards. (One furlong is 220 yards.)

int main(int argc, const char *argv[])
{
	long x;	
	cout << "Please input the distance: ";
	cin >> x;
	long y = 220 * x;
	cout << "yard is: " << y << endl;
    return 0;
}

3. Write a C++ program that uses three user-defined functions (counting main() as one) and produces the following output:
    Three blind mice
    Three blind mice
    See how they run
    See how they run
One function, called two times, should produce the first two lines, and the remaining function, also called twice, should produce the remaining output. 

const char *mouse(void)
{
	return "Three blind mice";
}

const char *run(void)
{
	return "See how they run";
}

int main(int argc, const char *argv[])
{
	cout << mouse() << endl;
	cout << mouse() << endl;
	cout << run() << endl;
	cout << run() << endl;
	return 0;
}

4. Write a program that asks the user to enter his or her age.The program then should display the age in months:
    Enter your age: 2 9
    Your age in months is 384.

int AgeToMonth(int age)
{
	int month;
	month = age * 12;
	return month;}

int main(int argc, const char *argv[])
{
	int age;
	cout << "Enter your age: ";
	cin >> age;
	cout << "Your age in months is: " << AgeToMonth(age) << endl;
	return 0;
}

5. Write a program that has main() call a user-defined function that takes a Celsius temperature value as an argument and then returns the equivalent Fahrenheit value. The program should request the Celsius value as input from the user and display the result, as shown in the following code:
    Please enter a Celsius value: 20
    20 degrees Celsius is 68 degrees Fahrenheit.
For reference, here is the formula for making the conversion:
    Fahrenheit = 1.8 × degrees Celsius + 32.0

float CelToFah(float Cel)
{
	return Cel * 1.8 + 32.0;
}

int main(int argc, const char *argv[])
{
	float Cel;
	cout << "Please enter a Celsius value: ";
	cin >> Cel;
	float Fah = CelToFah(Cel);
	cout << Cel << " degrees Celsius is " << Fah << " degrees Fahrenheit" << endl;
	return 0;
}

Write a program that has main() call a user-defined function that takes a distance in light years as an argument and then returns the distance in astronomical units. The program should request the light year value as input from the user and display the result, as shown in the following code:
    Enter the number of light years: 4.2
    4.2 light years = 265608 astronomical units.
An astronomical unit is the average distance from the earth to the sun (about 150,000,000 km or 93,000,000 miles), and a light year is the distance light travels in a year (about 10 trillion kilometers or 6 trillion miles). (The nearest star after the sun is about 4.2 light years away.) Use type double (as in Listing 2.4) and this conversion factor:
    1 light year = 63,240 astronomical units

double LyToAu(double ly)
{
	return ly * 63240;
}

int main(int argc, const char *argv[])
{
	double ly;
	cout << "Enter the number of light years: ";
	cin >> ly;
	cout << ly << " light years = " << LyToAu(ly) << " astronomical units." << endl;
	return 0;
}

7. Write a program that asks the user to enter an hour value and a minute value.The  main() function should then pass these two values to a type void function that displays the two values in the format shown in the following sample run:
    Enter the number of hours: 9
    Enter the number of minutes: 28
    Time: 9:28

void time(int hour, int min)
{
	cout << "Time: " << hour << ":" << min << endl;
	return;
}

int main(int argc, const char *argv[])
{
	int hour, min;
	cout << "Enter the number of hours: ";
	cin >> hour;
	cout << "Enter the number of minutes: ";
	cin >> min;
	time(hour, min);
	return 0;
}