On the TutsPlus.com site they've continued their series of posts introducing you to some of the basic functionality included with the PHP language. In this latest tutorial they focus on integers, floats, and number strings and how to determine which you're using.
Working with numbers in PHP seems to be a trivial concept, but it can be quite confusing. It looks easy at first because PHP provides automatic type conversion. For example, you can assign an integer value to a variable, and the type of that variable will be an integer. On the next line, you can assign a string to the same variable, and the type will change to a string. Unfortunately, this automatic conversion can sometimes break your code.
There are a lot of types for numeric values as well. In this tutorial, you'll learn about integers and floats in PHP, as well as the functions which can be used to determine the type of numbers that we are dealing with and convert between them. You'll also learn how to convert integers and floats to and from numerical strings.
The post starts by giving a summary of each of the types - integers and floats - along with the concepts of infinity and NaN. It then covers the use of "numerical strings" in PHP and the automatic type switching that can happen when using them with actual number values. The post wraps up with examples of how to cast values from strings to integers (and back) along with some final thoughts.