C++ Primer Plus

2. Modify Listing 15.11 so that the two exception types are classes derived from the logic_error class provided by the header file. Have each what() method report the function name and the nature of the problem. The exception objects need not hold the bad values; they should just support the what() method.

3. This exercise is the same as Programming Exercise 2, except that the exceptions should be derived from a base class (itself derived from logic_error) that stores the two argument values, the exceptions should have a method that reports these values as well as the function name, and a single catch block that catches the base-class exemption should be used for both exceptions, with either exception causing the loop to terminate.

4. Listing 15.16 uses two catch blocks after each try block so that the nbad_index exception leads to the label_val() method being invoked. Modify the program so that it uses a single catch block after each try block and uses RTTI to handle invoking label_val() only when appropriate.

16. The string Class and the Standard Template Library

In this chapter you’ll learn about the following:

• The standard C++ string class

• The auto_ptr, unique_ptr, and shared_ptr templates

• The Standard Template Library (STL)

• Container classes

• Iterators

• Function objects (functors)

• STL algorithms

• The initializer_list template

By now you are familiar with the C++ goal of reusable code. One of the big payoffs is when you can reuse code written by others. That’s where class libraries come in. There are many commercially available C++ class libraries, and there are also libraries that come as part of the C++ package. For example, you’ve been using the input/output classes supported by the ostream header file. This chapter looks at other reusable code available for your programming pleasure.

You’ve already encountered the string class, and this chapter examines it more extensively. Then the chapter looks at “smart pointer” template classes that make managing dynamic memory a bit easier. Next, the chapter looks at the Standard Template Library (STL), a collection of useful templates for handling various kinds of container objects. The STL exemplifies the programming paradigm called generic programming. Finally, the chapter looks at the initializer_list template class, the C++11 addition that enables using initializer-list syntax with STL objects.

The string Class

Many programming applications need to process strings. C provides some support with its string.h (cstring in C++) family of string functions, and many early C++ implementations provide home-grown classes to handle strings. Chapter 4, “Compound Types,” introduced the ANSI/ISO C++ string class. Chapter 12, “Classes and Dynamic Memory Allocation,” with its modest String class, illustrates some aspects of designing a class to represent strings.

Recall that the string class is supported by the string header file. (Note that the string.h and cstring header files support the C library string functions for C-style strings, not the string class.) The key to using a class is knowing its public interface, and the string class has an extensive set of methods, including several constructors, overloaded operators for assigning strings, concatenating strings, comparing strings, and accessing individual elements, as well as utilities for finding characters and substrings in a string, and more. In short, the string class has lots to offer.

Constructing a String