Memory Access

Arrays and pointers are low-level building blocks of C programs that provide fast access to hardware memory. This chapter discusses the different ways to organize and access memory.

22.1

Pointer Pathology

504

22.2

Further Pointer Pathology with Heap Memory

506

22.3

Memory Access Summary

509

22.4

Introduction to Arrays

509

22.5

Pointer Arithmetic

510

22.6

Arrays, Functions, and Return Values

511

22.7

Different Kinds of Arrays

513

22.8

Valid Pointer Operations

513

22.9

What Happens If new Fails?

515

22.10

Chapter Summary

519

Direct manipulation of memory entails some serious risks and requires good practices and thorough testing to avoid serious errors. Improper use of pointers and dynamic memory can cause program crashes that result from heap corruption and memory leaks. Heap corruption is especially difficult to debug because it generally leads to segmentation faults that halt the program at a point in the code that may be far from the point at which the heap became corrupted.

Both Qt and Standard Library container classes permit the safe use of dynamic memory without adversely affecting performance.[1] Arrays are used to implement most container classes but are hidden from client code. The safety factors come from the careful design of each container API so that actions that might produce memory problems are not permitted.

[1] In the sequel, whenever we use the term container, with no further qualification, we mean Qt or Standard Library container.

Qt offers many containers, ranging from high-level template classes such as the ones we discussed in Section 10.2 to low-level containers such as QBitArray and QByteArray.

Generally, when writing applications that reuse those containers, it is easy to avoid the use of arrays entirely. When Qt is not available, or when you are writing an interface to C code, you may need to use arrays and pointers and work directly with allocated memory.


Part I: Introduction to C++ and Qt 4

C++ Introduction

Classes

Introduction to Qt

Lists

Functions

Inheritance and Polymorphism

Part II: Higher-Level Programming

Libraries

Introduction to Design Patterns

QObject

Generics and Containers

Qt GUI Widgets

Concurrency

Validation and Regular Expressions

Parsing XML

Meta Objects, Properties, and Reflective Programming

More Design Patterns

Models and Views

Qt SQL Classes

Part III: C++ Language Reference

Types and Expressions

Scope and Storage Class

Statements and Control Structures

Memory Access

Chapter Summary

Inheritance in Detail

Miscellaneous Topics

Part IV: Programming Assignments

MP3 Jukebox Assignments

Part V: Appendices

MP3 Jukebox Assignments

Bibliography

MP3 Jukebox Assignments



An Introduction to Design Patterns in C++ with Qt 4
An Introduction to Design Patterns in C++ with Qt 4
ISBN: 0131879057
EAN: 2147483647
Year: 2004
Pages: 268

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