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Flash automatically assigns data types to the following kinds of language elements, as discussed in the next section, Automatic data typing:
However, you can also explicitly assign data types to items, which can help prevent or diagnose certain errors in your scripts. For more information, see Strict data typing.
In Flash, you do not need to explicitly define an item as holding either a number, a string, or other data type. Flash determines the data type of an item when it is assigned:
var x = 3;
In the expression var x = 3, Flash evaluates the element on the right side of the operator and determines that it is of the number data type. A later assignment may change the type of x; for example, the statement x = "hello" changes the type of x to a string. A variable that hasn't been assigned a value has a type of undefined.
ActionScript converts data types automatically when an expression requires it. For example, when you pass a value to the trace() action, trace() automatically converts the value to a string and sends it to the Output panel. In expressions with operators, ActionScript converts data types as needed; for example, when used with a string, the + operator expects the other operand to be a string.
"Next in line, number " + 7
ActionScript converts the number 7 to the string "7" and adds it to the end of the first string, resulting in the following string:
"Next in line, number 7"
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