Variables in ActionScript3
A variable is a named location in memory where you can store values. Before you can use a variable, you must declare it using a good name
and a type
. You can also give it an initial value. For these examples, we will use int (integer values)
A variable dx is declared as shown below. Notice that a variable can be given an optional initial value when it is declared.
var dx: int=0;
var dy: int=0;
- If you declare a variable inside a function, it is known only inside that function.
- If you want to use a variable anywhere in the movie, declare it in frame 1, but not inside any function.
- A variable that is declared outside of any functions is said to be global.
- A variable that is declared inside a function is said to be local to that function.
A variable can be assigned a value with the assignment statement.
The format is: variable = newvalue;
The new value can be a constant: dx = 5;
The new value can be another variable: dx = dy;
The new value can be a property: dx = ball.y;
The new value can be an expression: x = y/3;
It can even use its current value in the expression: x = x + 1;
The last statement is called incrementing and can also be written: x++;
The last two statements assign a new value to x that is one more than its current value.