- •Thinking in C++ 2nd edition Volume 2: Standard Libraries & Advanced Topics
- •Preface
- •What’s new in the second edition
- •What’s in Volume 2 of this book
- •How to get Volume 2
- •Prerequisites
- •Learning C++
- •Goals
- •Chapters
- •Exercises
- •Exercise solutions
- •Source code
- •Language standards
- •Language support
- •The book’s CD ROM
- •Seminars, CD Roms & consulting
- •Errors
- •Acknowledgements
- •Library overview
- •1: Strings
- •What’s in a string
- •Creating and initializing C++ strings
- •Initialization limitations
- •Operating on strings
- •Appending, inserting and concatenating strings
- •Replacing string characters
- •Concatenation using non-member overloaded operators
- •Searching in strings
- •Finding in reverse
- •Finding first/last of a set
- •Removing characters from strings
- •Stripping HTML tags
- •Comparing strings
- •Using iterators
- •Iterating in reverse
- •Strings and character traits
- •A string application
- •Summary
- •Exercises
- •2: Iostreams
- •Why iostreams?
- •True wrapping
- •Iostreams to the rescue
- •Sneak preview of operator overloading
- •Inserters and extractors
- •Manipulators
- •Common usage
- •Line-oriented input
- •Overloaded versions of get( )
- •Reading raw bytes
- •Error handling
- •File iostreams
- •Open modes
- •Iostream buffering
- •Seeking in iostreams
- •Creating read/write files
- •User-allocated storage
- •Output strstreams
- •Automatic storage allocation
- •Proving movement
- •A better way
- •Output stream formatting
- •Internal formatting data
- •Format fields
- •Width, fill and precision
- •An exhaustive example
- •Formatting manipulators
- •Manipulators with arguments
- •Creating manipulators
- •Effectors
- •Iostream examples
- •Code generation
- •Maintaining class library source
- •Detecting compiler errors
- •A simple datalogger
- •Generating test data
- •Verifying & viewing the data
- •Counting editor
- •Breaking up big files
- •Summary
- •Exercises
- •3: Templates in depth
- •Nontype template arguments
- •Typedefing a typename
- •Using typename instead of class
- •Function templates
- •A string conversion system
- •A memory allocation system
- •Type induction in function templates
- •Taking the address of a generated function template
- •Local classes in templates
- •Applying a function to an STL sequence
- •Template-templates
- •Member function templates
- •Why virtual member template functions are disallowed
- •Nested template classes
- •Template specializations
- •A practical example
- •Pointer specialization
- •Partial ordering of function templates
- •Design & efficiency
- •Preventing template bloat
- •Explicit instantiation
- •Explicit specification of template functions
- •Controlling template instantiation
- •Template programming idioms
- •Summary
- •Containers and iterators
- •STL reference documentation
- •The Standard Template Library
- •The basic concepts
- •Containers of strings
- •Inheriting from STL containers
- •A plethora of iterators
- •Iterators in reversible containers
- •Iterator categories
- •Input: read-only, one pass
- •Output: write-only, one pass
- •Forward: multiple read/write
- •Bidirectional: operator--
- •Random-access: like a pointer
- •Is this really important?
- •Predefined iterators
- •IO stream iterators
- •Manipulating raw storage
- •Basic sequences: vector, list & deque
- •Basic sequence operations
- •vector
- •Cost of overflowing allocated storage
- •Inserting and erasing elements
- •deque
- •Converting between sequences
- •Cost of overflowing allocated storage
- •Checked random-access
- •list
- •Special list operations
- •list vs. set
- •Swapping all basic sequences
- •Robustness of lists
- •Performance comparison
- •A completely reusable tokenizer
- •stack
- •queue
- •Priority queues
- •Holding bits
- •bitset<n>
- •vector<bool>
- •Associative containers
- •Generators and fillers for associative containers
- •The magic of maps
- •A command-line argument tool
- •Multimaps and duplicate keys
- •Multisets
- •Combining STL containers
- •Creating your own containers
- •Summary
- •Exercises
- •5: STL Algorithms
- •Function objects
- •Classification of function objects
- •Automatic creation of function objects
- •Binders
- •Function pointer adapters
- •SGI extensions
- •A catalog of STL algorithms
- •Support tools for example creation
- •Filling & generating
- •Example
- •Counting
- •Example
- •Manipulating sequences
- •Example
- •Searching & replacing
- •Example
- •Comparing ranges
- •Example
- •Removing elements
- •Example
- •Sorting and operations on sorted ranges
- •Sorting
- •Example
- •Locating elements in sorted ranges
- •Example
- •Merging sorted ranges
- •Example
- •Set operations on sorted ranges
- •Example
- •Heap operations
- •Applying an operation to each element in a range
- •Examples
- •Numeric algorithms
- •Example
- •General utilities
- •Creating your own STL-style algorithms
- •Summary
- •Exercises
- •Perspective
- •Duplicate subobjects
- •Ambiguous upcasting
- •virtual base classes
- •The "most derived" class and virtual base initialization
- •"Tying off" virtual bases with a default constructor
- •Overhead
- •Upcasting
- •Persistence
- •MI-based persistence
- •Improved persistence
- •Avoiding MI
- •Mixin types
- •Repairing an interface
- •Summary
- •Exercises
- •7: Exception handling
- •Error handling in C
- •Throwing an exception
- •Catching an exception
- •The try block
- •Exception handlers
- •Termination vs. resumption
- •The exception specification
- •Better exception specifications?
- •Catching any exception
- •Rethrowing an exception
- •Uncaught exceptions
- •Function-level try blocks
- •Cleaning up
- •Constructors
- •Making everything an object
- •Exception matching
- •Standard exceptions
- •Programming with exceptions
- •When to avoid exceptions
- •Not for asynchronous events
- •Not for ordinary error conditions
- •Not for flow-of-control
- •You’re not forced to use exceptions
- •New exceptions, old code
- •Typical uses of exceptions
- •Always use exception specifications
- •Start with standard exceptions
- •Nest your own exceptions
- •Use exception hierarchies
- •Multiple inheritance
- •Catch by reference, not by value
- •Throw exceptions in constructors
- •Don’t cause exceptions in destructors
- •Avoid naked pointers
- •Overhead
- •Summary
- •Exercises
- •8: Run-time type identification
- •The “Shape” example
- •What is RTTI?
- •Two syntaxes for RTTI
- •Syntax specifics
- •Producing the proper type name
- •Nonpolymorphic types
- •Casting to intermediate levels
- •void pointers
- •Using RTTI with templates
- •References
- •Exceptions
- •Multiple inheritance
- •Sensible uses for RTTI
- •Revisiting the trash recycler
- •Mechanism & overhead of RTTI
- •Creating your own RTTI
- •Explicit cast syntax
- •Summary
- •Exercises
- •9: Building stable systems
- •Shared objects & reference counting
- •Reference-counted class hierarchies
- •Finding memory leaks
- •An extended canonical form
- •Exercises
- •10: Design patterns
- •The pattern concept
- •The singleton
- •Variations on singleton
- •Classifying patterns
- •Features, idioms, patterns
- •Basic complexity hiding
- •Factories: encapsulating object creation
- •Polymorphic factories
- •Abstract factories
- •Virtual constructors
- •Destructor operation
- •Callbacks
- •Observer
- •The “interface” idiom
- •The “inner class” idiom
- •The observer example
- •Multiple dispatching
- •Visitor, a type of multiple dispatching
- •Efficiency
- •Flyweight
- •The composite
- •Evolving a design: the trash recycler
- •Improving the design
- •“Make more objects”
- •A pattern for prototyping creation
- •Trash subclasses
- •Parsing Trash from an external file
- •Recycling with prototyping
- •Abstracting usage
- •Applying double dispatching
- •Implementing the double dispatch
- •Applying the visitor pattern
- •More coupling?
- •RTTI considered harmful?
- •Summary
- •Exercises
- •11: Tools & topics
- •The code extractor
- •Debugging
- •Trace macros
- •Trace file
- •Abstract base class for debugging
- •Tracking new/delete & malloc/free
- •CGI programming in C++
- •Encoding data for CGI
- •The CGI parser
- •Testing the CGI parser
- •Using POST
- •Handling mailing lists
- •Maintaining your list
- •Mailing to your list
- •A general information-extraction CGI program
- •Parsing the data files
- •Summary
- •Exercises
- •General C++
- •My own list of books
- •Depth & dark corners
- •Design Patterns
- •Index
However, you may want to continue using the file, by seeking to an earlier position and reading more data. To correct the condition, simply call the clear( ) member function.7
File iostreams
Manipulating files with iostreams is much easier and safer than using cstdio in C. All you do to open a file is create an object; the constructor does the work. You don’t have to explicitly close a file (although you can, using the close( ) member function) because the destructor will close it when the object goes out of scope.
To create a file that defaults to input, make an ifstream object. To create one that defaults to output, make an ofstream object.
Here’s an example that shows many of the features discussed so far. Note the inclusion of <fstream> to declare the file I/O classes; this also includes <iostream>.
//: C02:Strfile.cpp
//Stream I/O with files
//The difference between get() & getline() #include "../require.h"
#include <fstream> #include <iostream> using namespace std;
int main() {
const int sz = 100; // Buffer size; char buf[sz];
{
ifstream in("Strfile.cpp"); // Read assure(in, "Strfile.cpp"); // Verify open ofstream out("Strfile.out"); // Write assure(out, "Strfile.out");
int i = 1; // Line counter
// A less-convenient approach for line input: while(in.get(buf, sz)) { // Leaves \n in input in.get(); // Throw away next character (\n)
cout << buf << endl; // Must add \n
// File output just like standard I/O:
7 Newer implementations of iostreams will still support this style of handling errors, but in some cases will also throw exceptions.
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out << i++ << ": " << buf << endl;
}
} // Destructors close in & out
ifstream in("Strfile.out"); assure(in, "Strfile.out");
// More convenient line input: while(in.getline(buf, sz)) { // Removes \n
char* cp = buf; while(*cp != ':')
cp++;
cp += 2; // Past ": "
cout << cp << endl; // Must still add \n
}
} ///:~
The creation of both the ifstream and ofstream are followed by an assure( ) to guarantee the file has been successfully opened. Here again the object, used in a situation where the compiler expects an integral result, produces a value that indicates success or failure. (To do this, an automatic type conversion member function is called. These are discussed in Chapter XX.)
The first while loop demonstrates the use of two forms of the get( ) function. The first gets characters into a buffer and puts a zero terminator in the buffer when either sz – 1 characters have been read or the third argument (defaulted to ‘\n’) is encountered. get( ) leaves the terminator character in the input stream, so this terminator must be thrown away via in.get( ) using the form of get( ) with no argument, which fetches a single byte and returns it as an int. You can also use the ignore( ) member function, which has two defaulted arguments. The first is the number of characters to throw away, and defaults to one. The second is the character at which the ignore( ) function quits (after extracting it) and defaults to EOF.
Next you see two output statements that look very similar: one to cout and one to the file out. Notice the convenience here; you don’t need to worry about what kind of object you’re dealing with because the formatting statements work the same with all ostream objects. The first one echoes the line to standard output, and the second writes the line out to the new file and includes a line number.
To demonstrate getline( ), it’s interesting to open the file we just created and strip off the line numbers. To ensure the file is properly closed before opening it to read, you have two choices. You can surround the first part of the program in braces to force the out object out of scope, thus calling the destructor and closing the file, which is done here. You can also call close( ) for both files; if you want, you can even reuse the in object by calling the open( ) member function (you can also create and destroy the object dynamically on the heap as is in Chapter XX).
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