Next 10,000 tvarps: 10% tax
Next 20,000 tvarps: 15% tax
Tvarps after 35,000: 20% tax
For example, someone earning 38,000 tvarps would owe 5,000 × 0.00 + 10,000 × 0.10 + 20,000 × 0.15 + 3,000 × 0.20, or 4,600 tvarps. Write a program that uses a loop to solicit incomes and to report tax owed. The loop should terminate when the user enters a negative number or non-numeric input.
6. Put together a program that keeps track of monetary contributions to the Society for the Preservation of Rightful Influence. It should ask the user to enter the number of contributors and then solicit the user to enter the name and contribution of each contributor. The information should be stored in a dynamically allocated array of structures. Each structure should have two members: a character array (or else a string object) to store the name and a double member to hold the amount of the contribution. After reading all the data, the program should display the names and amounts donated for all donors who contributed $10,000 or more. This list should be headed by the label Grand Patrons. After that, the program should list the remaining donors. That list should be headed Patrons. If there are no donors in one of the categories, the program should print the word “none.” Aside from displaying two categories, the program need do no sorting.
7. Write a program that reads input a word at a time until a lone q is entered. The program should then report the number of words that began with vowels, the number that began with consonants, and the number that fit neither of those categories. One approach is to use isalpha() to discriminate between words beginning with letters and those that don’t and then use an if or switch statement to further identify those passing the isalpha() test that begin with vowels. A sample run might look like this:
Enter words (q to quit):
The 12 awesome oxen ambled
quietly across 15 meters of lawn. q
5 words beginning with vowels
4 words beginning with consonants
2 others
8. Write a program that opens a text file, reads it character-by-character to the end of the file, and reports the number of characters in the file.
9. Do Programming Exercise 6 but modify it to get information from a file. The first item in the file should be the number of contributors, and the rest of the file should consist of pairs of lines, with the first line of each pair being a contributor’s name and the second line being a contribution. That is, the file should look like this:
4
Sam Stone
2000
Freida Flass
100500
Tammy Tubbs
5000
Rich Raptor
55000
7. Functions: C++’s Programming Modules
In this chapter you’ll learn about the following:
• Function basics
• Function prototypes
• Passing function arguments by value
• Designing functions to process arrays
• Using const pointer parameters
• Designing functions to process text strings
• Designing functions to process structures
• Designing functions to process objects of the string class
• Functions that call themselves (recursion)
• Pointers to functions
Fun is where you find it. Look closely, and you can find it in functions. C++ comes with a large library of useful functions (the standard ANSI C library plus several C++ classes), but real programming pleasure comes with writing your own functions. (On the other hand, real programming productivity can come with learning more about what you can do with the STL and the BOOST C++ libraries.) This chapter and Chapter 8, “Adventures in Functions,” examine how to define functions, convey information to them, and retrieve information from them. After reviewing how functions work, this chapter concentrates on how to use functions in conjunction with arrays, strings, and structures. Finally, it touches on recursion and pointers to functions. If you’ve paid your C dues, you’ll find much of this chapter familiar. But don’t be lulled into a false sense of expertise. C++ has made several additions to what C functions can do, and Chapter 8 deals primarily with those. Meanwhile, let’s attend to the fundamentals.
Function Review
Let’s review what you’ve already seen about functions. To use a C++ function, you must do the following:
• Provide a function definition
• Provide a function prototype
• Call the function
If you’re using a library function, the function has already been defined and compiled for you. Also you can and should use a standard library header file to provide the prototype. All that’s left to do is call the function properly. The examples so far in this book have done that several times. For example, the standard C library includes the strlen() function for finding the length of the string. The associated standard header file cstring contains the function prototype for strlen() and several other string-related functions. This advance work allows you to use the strlen() function in programs without further worries.