Tag: Programming
Adding ActionScript to Multiple Instances
Author BradPosted on Categories ActionScript, Flash, Tutorials I wrote a small snippet of ActionScript 2.0 the other day that I was quite proud of. It actually isn’t a very complicated block of code, but I was having trouble making a movieclip do what I wanted so I was quite pleased when I finally got it to work.
Here was my problem:
I had a movieclip, twenty-four frames long, with twenty-three buttons inside. When the mouse moved over each button, the movieclip was supposed to go to a different frame. I didn’t want to code each button individually because that can be tedious, so I employed a method I have often used to add the same code to multiple buttons. First I gave the timeline a name by assigning it to a variable:
var menus:MovieClip = this;
My buttons inside the movieclip were named btn1 through btn23, so I then created a for statement like so:
for (var i=1; i< =23; i++) {
t = menus[“btn”+i];
t.onRollOver = function() {
gotoAndStop(i+1);
}
t.onRollOut = function() {
gotoAndStop(1);
}
}
Using the temporary variables t and i, I was able to assign onRollOver and onRollOut functions to each button. The code actually worked really well when the mouse rolled off the buttons, but when the mouse rolled over the buttons, the movieclip always went to Frame 24 (23 + 1), no matter which button it was over. Obviously, this wasn’t going to work.
I tried several things to make the code work, and had no luck. For some reason, whenever I used the i variable in referencing the frame to go to, it only registered as being equal to 23. I had to figure out a way to capture the value of i at each iteration. Then it occured to me. Since i wasn’t working, maybe I could reference the object directly, using the instance name to tell the movieclip which frame to go to. That was easy enough to do using this._name, but I still had the problem of getting rid of the btn part of the instance names. That was when I remembered substring. I rewrote my code to convert the substring of each instance name to an integer, added 1, and it worked perfectly. My code now looked like this:
var menus:MovieClip = this;
for (var i=1; i < =23; i++) {
t = menus[“btn”+i];
t.onRollOver = function() {
gotoAndStop(int(substring(this._name, 4, this._name.length)) + 1);
}
t.onRollOut = function() {
gotoAndStop(1);
}
}
Variables and Data Types in PHP
Author BradPosted on Categories PHP, Tutorials Continued from Understanding Variables:
PHP variables must also conform to a set of rules. Variable names must start with a dollar sign. They can contain any combination of strings, numbers, and underscores, but the first character after the dollar sign cannot be a number. PHP variables are also case-sensitive.
PHP variables don’t need an initial value when they are created, and they don’t need to be declared a specific data type either.
PHP has several built-in data types:
- boolean – a data type with only two possible values: true or false
- integer – any positive or negative whole number, or a zero
- float – numbers that are too large or too small to be represented as integers
- string – a series of alphanumeric characters, numbers, and punctuation marks
- array – a data type which can hold several different values
- object – built-in or user-defined classes of data; a collection of properties or attributes
- resource – a variable holding a reference to an external resource, like a MySQL database
- NULL – a special data value that has no value and means nothing; not the same as zero
When using integers, a leading 0 ( zero ) is used to specify that the integer is octal, and a leading 0x or 0X is used to specify hexadecimal. A floating point number can contain either a decimal or an “e” to represent “ten to the power of” in scientific notation, or both.
Note: ActionScript and JavaScript also use arrays, but they aren’t listed as a basic data type in the official documentation, as far as I’ve been able to discover, while arrays are listed as one of the eight main data types supported by PHP. While most of us just use arrays without considering whether they are a data type or not, I have endeavored to follow the various documentation in these articles. I apologize for any confusion this may cause.
Variables and Data Types in JavaScript
Author BradPosted on Categories JavaScript, Tutorials Continued from Understanding Variables:
Like other languages, JavaScript variables must also conform to certain rules. Variable names must start with either a letter or an underscore, but they can contain numbers later on in the name. JavaScript variables are also case-sensitive.
As in ActionScript, JavaScript variable types do not need to be specified when they are created and data types are converted automatically as needed.
JavaScript has several built-in data types:
- Boolean – a data type with only two possible values: true or false
- Null – a special data value that has no value and means nothing; not the same as zero
- Number – any series of numeric values, including integers and floating point numbers; can be expressed in decimal ( base 10 ), hexadecimal ( base 16 ), or octal ( base 8 )
- Object – built-in or user-defined classes of data; a collection of properties or attributes
- String – a series of alphanumeric characters, numbers, and punctuation marks
- Undefined – a special data value representing an absence of data; default value for variables declared without a value
When using integers in the Number data type, a leading 0 ( zero ) is used to specify that the integer is octal, and a leading 0x or 0X is used to specify hexadecimal. A floating point number can contain a either a decimal or an “e” to represent “ten to the power of” in scientific notation, or both.
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Variables and Data Types in ActionScript
Author BradPosted on Categories ActionScript, Tutorials Continued from Understanding Variables:
Like most programming languages, ActionScript variables follow a set of rules when it comes to naming. ActionScript variable names can have letters, numbers, dollar signs, and underscores, but they cannot start with a number. ActionScript variables are also case-sensitive.
ActionScript variables are a little unusual in that any variable can store any type of data. When a piece of data is assigned to a variable, the interpreter automatically changes the variable type to whatever type the data is. In programming languages like Java and C++, data of the wrong type is converted to the variable’s data type instead of the other way around, or an error is caused in the program.
Alternatively, ActionScript variable types can be set when the variable is declared.
ActionScript 2.0 has several built-in data types:
- Boolean – a data type with only two possible values: true or false
- MovieClip – a special data type used for controlling movie clip instances
- null – a special data value representing an absence of data; default value for variables declared without a value
- Number – any series of numeric values, including integers, unsigned integers, and floating point numbers; mainly used for counting and mathematical equations
- Object – built-in or user-defined classes of data; a collection of properties or attributes
- String – a series of alphanumeric characters, numbers, and punctuation marks
- undefined – same as the null data type; default value for instances of the Object class
- Void – special data type used to designate functions that don’t return a value
ActionScript 3.0 also adds two more data types:
- int – a 32-bit integer between -231 and 231-1
- uint – a 32-bit unsigned integer (either positive or zero) between 0 and 232-1
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Understanding Variables
Author BradPosted on Categories ActionScript, JavaScript, PHP, Tutorials While not technically tutorials, I have decided to post a series of articles about variables for Web programming newbies. Variables are an essential element for anyone wishing to do Web programming. They are also an integral part of many technologies, including JavaScript, ActionScript, and PHP.
To begin with, what is a variable? A technical definition would be somewhere along the lines of : A pointer to a location in memory where a temporary value can be stored for use in a program. To the common person that may not make much sense, so I prefer a different definition: A container which holds a value that can be changed. Simply put, a variable is a key word that represents a temporary value. If it helps, you can think of variables as having a variable value. Generally, this value can be changed through instructions given by a program, but some variables are unchangeable depending on the scripting language in use. Many languages have built-in variables which keep a constant value.
Most scripting languages also have some sort of method for deciding the pattern of variable names. In general, variable names may contain letters, numbers, underscores, and dollar signs, but they cannot start with a number. They also cannot contain spaces. While variable names can generally be of any length, if they are too long they become unmanageable.
Many languages are case-sensitive, so it is also a good idea to pay attention to whether your variable names include capital or lowercase letters. In languages where variable names are not case-sensitive, a program may confuse one variable with another if care is not taken during naming. A variable named my_var will look exactly the same as a different variable named My_Var. As a rule of thumb, I never create variables using capital letters. That way, regardless of the language I’m using I will never have conflicting variable names.
In the continuation of my Variables series, I plan on looking at the use of variables in a couple of different coding languages; specifically ActionScript, JavaScript, and PHP. Stay tuned for more.
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