Working with Variables in Flash: String functions
Difficulty: Beginner
Here is an overview of basic actionscript String functions you can use to manipulate text in actionscript.
You can manipulate variables with actionscript using numeric operators such as: multiplication or subtraction. Here are some common cases of variable manipulation with numeric operators.
Isolating characters in a string with the substr() function
the substr() function has to be passed 2 parameters in order for it to return a value: start and length. The start parameter defines where to start isolating characters and the length defines how many characters to isolate. Take a look at the code below to see the substr() function in action:
studentName = "Jack Simpson";
firstName = studentName.substr(0,4); // isolate the first 4 characters starting form 0 and store them in a variable
trace(firstName); // Displays: Jack
Finding characters in a string with the indexOf() function
The indexOf() function is a very useful one. It can find the first occurrence a character in a string and return its position. If no occurrence is found, the function will return -1. Let's say you want to validate that an email is valid in it's form, you would have to verify three things:
1. There is an "@" in the email
2. There is a "." in the email
3. There's no empty spaces in the email
Let's look at how we would do this with actionscript:
email = "john@website.com";
isValid = true;
if (email.indexOf("@") == -1) {
isValid = false;
}
if (email.indexOf(".") == -1) {
isValid = false;
}
if (email.indexOf(" ") != -1) {
isValid = false;
}
trace(isValid); // displays: true because in this case the email is a valid one.
Finding the character at a specific position in a string with the charAt() function
Using the charAt() function is pretty simple, let's say you want to put the first character of a string in a variable, you could write the actonscript code below:
firstName = "John";
firstChar = firstName.charAt(0);
trace(firstChar); // displays: "J" the first character of the firstName variable.
Note: actionscript is a zero-based language, therefore the first element in a list is element 0 not element 1. That's why in this case firstName.charAt(0); returns "J".
Counting the number of letters in a string
You can find the number of characters in a string by accessing the length property. Below is a simple example of how you can count letters in a string with actionscript.
string1 = "Hello";
nbLetters = string1.length;
trace(nbLetters); // displays: 5 the number of character in the string1 variable.
Next Flash Tutorial > Working with variables part 3 (coming soon) |
