C++ Primer Plus

3. Write a program that asks the user to enter a latitude in degrees, minutes, and seconds and that then displays the latitude in decimal format. There are 60 seconds of arc to a minute and 60 minutes of arc to a degree; represent these values with symbolic constants. You should use a separate variable for each input value. A sample run should look like this:

Enter a latitude in degrees, minutes, and seconds:

First, enter the degrees: 37

Next, enter the minutes of arc: 51

Finally, enter the seconds of arc: 19

37 degrees, 51 minutes, 19 seconds = 37.8553 degrees

4. Write a program that asks the user to enter the number of seconds as an integer value (use type long, or, if available, long long) and that then displays the equivalent time in days, hours, minutes, and seconds. Use symbolic constants to represent the number of hours in the day, the number of minutes in an hour, and the number of seconds in a minute. The output should look like this:

Enter the number of seconds: 31600000

31600000 seconds = 365 days, 17 hours, 46 minutes, 40 seconds

5. Write a program that requests the user to enter the current world population and the current population of the U.S. (or of some other nation of your choice). Store the information in variables of type long long. Have the program display the percent that the U.S. (or other nation’s) population is of the world’s population. The output should look something like this:

Enter the world's population: 6898758899

Enter the population of the US: 310783781

The population of the US is 4.50492% of the world population.

You can use the Internet to get more recent figures.

6. Write a program that asks how many miles you have driven and how many gallons of gasoline you have used and then reports the miles per gallon your car has gotten. Or, if you prefer, the program can request distance in kilometers and petrol in liters and then report the result European style, in liters per 100 kilometers.

7. Write a program that asks you to enter an automobile gasoline consumption figure in the European style (liters per 100 kilometers) and converts to the U.S. style of miles per gallon. Note that in addition to using different units of measurement, the U.S. approach (distance / fuel) is the inverse of the European approach (fuel / distance). Note that 100 kilometers is 62.14 miles, and 1 gallon is 3.875 liters. Thus, 19 mpg is about 12.4 l/100 km, and 27 mpg is about 8.7 l/100 km.

4. Compound Types

In this chapter you’ll learn about the following:

• Creating and using arrays

• Creating and using C-style strings

• Creating and using string-class strings

• Using the getline() and get() methods for reading strings

• Mixing string and numeric input

• Creating and using structures

• Creating and using unions

• Creating and using enumerations

• Creating and using pointers

• Managing dynamic memory with new and delete

• Creating dynamic arrays

• Creating dynamic structures

• Automatic, static, and dynamic storage

• The vector and array classes (an introduction)

Say you’ve developed a computer game called User-Hostile in which players match wits with a cryptic and abusive computer interface. Now you must write a program that keeps track of your monthly game sales for a five-year period. Or you want to inventory your accumulation of hacker-hero trading cards. You soon conclude that you need something more than C++’s simple basic types to meet these data requirements, and C++ offers something more—compound types. These are types built from the basic integer and floating-point types. The most far-reaching compound type is the class, that bastion of OOP toward which we are progressing. But C++ also supports several more modest compound types taken from C. The array, for example, can hold several values of the same type. A particular kind of array can hold a string, which is a series of characters. Structures can hold several values of differing types. Then there are pointers, which are variables that tell a computer where data is placed. You’ll examine all these compound forms (except classes) in this chapter, take a first look at new and delete and how you can use them to manage data, and take an introductory look at the C++ string class, which gives you an alternative way to work with strings.

Introducing Arrays

An array is a data form that can hold several values, all of one type. For example, an array can hold 60 type int values that represent five years of game sales data, 12 short values that represent the number of days in each month, or 365 float values that indicate your food expenses for each day of the year. Each value is stored in a separate array element, and the computer stores all the elements of an array consecutively in memory.

To create an array, you use a declaration statement. An array declaration should indicate three things:

• The type of value to be stored in each element

• The name of the array

• The number of elements in the array