Adobe 38043740 Developing Applications - Page 51

DEVELOPING COLDFUSION 9 APPLICATIONS 46 The CFML Programming Language Arrays Arrays are a way of storing multiple values in a table-like format that can have one or more dimensions. You create arrays using a function or an assignment statement: • The ColdFusion ArrayNew function creates an array and specifies its initial dimensions. For example, the following line creates an empty two-dimensional array: • A direct assignment creates an array and populates an array element. For example, the following line creates a twodimensional array and sets the value of row 1 column 2 to the current date. You reference elements using numeric indexes, with one index for each dimension, as shown in the preceding example. You can create arrays with up to three dimensions directly. However, there is no limit on array size or maximum dimension. To create arrays with more than three dimensions, create arrays of arrays. After you create an array, you can use functions or direct references to manipulate its contents. When you assign an existing array to a new variable, ColdFusion creates a new array and copies the old array's contents to the new array. The following example creates a copy of the original array: For more information on using arrays, see "Using Arrays and Structures" on page 82. Structures ColdFusion structures consist of key-value pairs, where the keys are text strings and the values can be any ColdFusion data type, including other structures. Structures let you build a collection of related variables that are grouped under a single name. To create a structure, use the ColdFusion StructNew function. For example, the following line creates a new, empty, structure called depts: You can also create a structure by assigning a value in the structure. For example, the following line creates a new structure called MyStruct with a key named MyValue, equal to 2: Note: In ColdFusion versions through ColdFusion 7, this line created a Variables scope variable named "MyStruct.MyValue" with the value 2. After you create a structure, you can use functions or direct references to manipulate its contents, including adding key-value pairs. You can use either of the following methods to reference elements stored in a structure: • StructureName.KeyName • StructureName["KeyName"] The following examples show these methods: depts.John="Sales" depts["John"]="Sales" When you assign an existing structure to a new variable, ColdFusion does not create a new structure. Instead, the new variable accesses the same data (location) in memory as the original structure variable. In other words, both variables are references to the same object. Last updated 1/20/2012