PHP 5 in Practice

4. Variables PHP provides the basic variable types: Boolean, integer, floating point, and strings. Strings and the number types were covered in Chapter 1, "Strings," and Chapter 2, "Numbers." In addition to these basic ty...

4.1. Determining Whether a Variable Is Equal to Another PHP is normally a programmer-friendly language. One of PHP's key features is that you almost never have to worry about what type your data is. It automatically converts data between data type...

4.2. Accessing a Variable Outside a Function, from Within it (Global Variables) When inside a function, you cannot, by default, access any variables from outside that function. This behavior can be changed, however, for specific variables by usi...

4.3. Keeping a Persistent Value Within a Function (Static Variables) Normally, after a function runs and exits, any variables created within the function is thrown away. At times, however, it can be useful to have a variable whose value persists b...

4.4. Having One Variable Refer to Another (References) Another useful task is having a variable that just points to another variable. This way it acts like an alias for that first variable. This is called a reference in PHP. The most common use ...

4.5. Using a Variable to Hold the Name of Another Variable An interesting programmer trick to keep up your sleeve is storing a variable name as a string in another variable and then referencing the original variable. PHP calls this variable vari...

4.6. Declaring a Constant Instead of a Variable Like variables, a constant is simply a way of assigning a symbolic, meaningful name to a value. A constant can be used in nearly every situation that a variable can be used in; however, there the sim...

4.7. Coalescing a List of Values to Determine the First Non-False Value Sometimes you have many values, and you simply want the first one of them that isn't false/empty/null/and so on. Most databases provide this functionality through a function...