PHP 5 in Practice

5. Arrays This chapter is deleted. Arrays are a necessary part of any computer language. However, in PHP, arrays are especially versatile. In most languages, arrays are implemented simply as many-dimensional tables; each element is accessed by a set of numbers. Each...

5.1. Superglobal Arrays and Their Usage The role of global variables in PHP was explained in Listing 4.2.1 in Chapter 4, "Variables"; however, PHP also has a set of variables known as superglobals. These all happen to be arrays and have ...

5.2. Stack Implementation A stack is a programming data structure that follows the rules of LIFO (Last In First Out). This is similar to a stack of plates. The last one placed on top of the stack, is the first one that is going to be taken back ...

5.3. Queue Implementation The opposite of a stack, a queue is a data structure that follows a FIFO (First In First Out) rule. This means that it works like a line at a movie theater. The person who gets in line first, gets served first. Similar t...

5.4. Sorting with User-Defined Comparisons The built-in sort functions can handle almost every basic sort you can think of: forward, backward, numeric, alphabetic, natural language, by key, by value. In fact, using array_multisort() you can even d...

5.5. Sorting with Alternative Algorithms The sort functions of PHP all use the Quicksort algorithm. They do this with good reason because this is the most generically useful sorting algorithm. Most of the time, it sorts in decent (if not the best)...

5.6. Recursive Handling of Multidimensional Arrays You may at times find yourself with a multidimensional array and needing to perform some task across all values in it. It would be cumbersome (and in some cases impossible) to actually perform the...

5.7. Performing Set Operations on Arrays Set theory describes a number of operations that you can perform on sets of values (in this case, arrays). PHP provides the capability to handle these, but it is worthwhile to explore them fully because the...

5.8. Matrix Math Execution Using Arrays An area in mathematics that lends itself to the use of arrays is matrix math. In oversimplified terms, matrix math is taking two different tables of numbers, performing some mathematical operation between th...