Sams Teach Yourself PHP in 24 Hours, Third Edition

Data Types

Different types of data take up different amounts of memory and can be treated differently when they are manipulated in a script. Some programming languages therefore demand that the programmer declare in advance which type of data a variable will contain. By contrast, PHP is loosely typed, which means it calculates data types as data is assigned to each variable. This is a mixed blessing. On the one hand, it means that variables can be used flexibly, holding a string at one point and an integer at another. On the other hand, this can lead to problems in larger scripts if you expect a variable to hold one data type when, in fact, it holds something completely different. You might have created code designed to work with an array variable, ...