Learning the iOS 4 SDK for JavaScript Programmers

C Arrays

The C language offers arrays that syntactically resemble JavaScript arrays. Except for the occasional need to pass a C array of values to CoreGraphics framework methods, you won’t use C arrays much for your app data because Cocoa Touch provides a far more robust version in the NSArray class (described in Chapter 8). I include C arrays here to make sure you understand the syntax you will see from time to time while perusing the iOS SDK documentation, or if you need to create a small array of values for graphics method arguments.

The data typing situation in creating a new array may seem odd at first, because the data type you declare is the data type of the elements of the array—which means that all elements of a C array must be of the same type. For example, if you wanted to generate an array that is to hold up to 10 integers, the declaration would be:

int myArray [10];

From there you can assign values by referencing spots in the array through array indices (zero-based), similar to the way you do it in JavaScript:

myArray[0] = 10;
myArray[1] = 20;
...
myArray[9] = 100;

Although JavaScript would merrily let you add more items to the array by continuing to use higher and higher index numbers, a C array maxes out at the number of elements specified in its declaration. You are free to iterate through arrays in for loops, but obtaining the number of elements in a C array for the conditional expression in a for construction takes a little extra work (there is no simple equivalent ...