Every character in a string has an index position in the string (an integer). The index position of the first character is 0. For example, in the following string, the character y is in position 0 and the character w is in position 5:

"yellow"

You can examine individual characters in various positions in a string using the charAt() method and the charCodeAt() method, as in this example:

var str:String = "hello world!";
for (var i:int = 0; i < str.length; i++)
{
    trace(str.charAt(i), "-", str.charCodeAt(i));
}

When you run this code, the following output is produced:

h - 104
e - 101
l - 108
l - 108
o - 111
- 32
w - 119
o - 111
r - 114
l - 108
d - 100
! - 33 

You can also use character codes to define a string using the fromCharCode() method, as the following example shows:

var myStr:String = String.fromCharCode(104,101,108,108,111,32,119,111,114,108,100,33);
        // Sets myStr to "hello world!"