ARRAYS & STRINGS

Arrays

An array is a collection of like variables that share a single name. The individual elements of an array are referenced by appending a subscript, in square brackets, behind the name. The subscript itself can be any legitimate C expression that yields an integer value, even a general expression. Therefore, arrays in C may be regarded as collections of like variables. Although arrays represent one of the simplest data structures, it has wide-spread usage in embedded systems.

Strings

Strings are similar to arrays with just a few differences. Usually, the array size is fixed, while strings can have a variable number of elements. Arrays can contain any data type (char short inteven other arrays) while strings are usually ASCII characters terminated with a NULL (0) character. In general we allow random access to individual array elements. On the other hand, we usually process strings sequentially character by character from start to end. Since these differences are a matter of semantics rather than specific limitations imposed by the syntax of the C programming language, the descriptions in this chapter apply equally to data arrays and character strings. String literals were discussed earlier in Chapter 3; in this chapter we will define data structures to hold our strings. In addition, C has a rich set of predefined functions to manipulate strings.