Chapter 4. Arrays and Pointers

CONTENTS

Section 4.1 Arrays	110
Section 4.2 Introducing Pointers	114
Section 4.3 C-Style Character Strings	130
Section 4.4 Multidimensioned Arrays	141
Chapter Summary	145
Defined Terms	145

The language defines two lower-level compound typesarrays and pointersthat are similar to vectors and iterators. Like a vector, an array holds a collection of objects of some type. Unlike vectors, arrays are fixed size; once an array is created, new elements cannot be added. Like iterators, pointers can be used to navigate among and examine the elements in an array.

Modern C++ programs should almost always use vectors and iterators in preference to the lower-level arrays and pointers. Well-designed programs use arrays and pointers only in the internals of class implementations where speed is essential.

Arrays are data structures that are similar to library vectors but are built into the language. Like a vector, an array is a container of objects of a single data type. The individual objects are not named; rather, each one is accessed by its position in the array.

Arrays have significant drawbacks compared to vectors: They are fixed size, and they offer no help to the programmer in keeping track of how big a given array is. There is no size operation on arrays. Similarly, there is no push_back to automatically add elements. If the array size needs to change, then the programmer must allocate a new, larger array and copy the elements into that new space.

Programs that rely on built-in arrays rather than using the standard vector are more error-prone and harder to debug.

Prior to the advent of the standard library, C++ programs made heavy use of arrays to hold collections of objects. Modern C++ programs should almost always use vectors instead of arrays. Arrays should be restricted to the internals of programs and used only where performance testing indicates that vectors cannot provide the necessary speed. However, there will be a large body of existing C++ code that relies on arrays for some time to come. Hence, all C++ programmers must know a bit about how arrays work.