Learn to Program with Small Basic

5 TextWindow.WriteLine(str)
6 TextWindow.WriteLine("This file has " + len + " characters.")
Listing 19-1: Demonstrating the ReadContents() method
This
is a
Here is the output of this program:
Test.
This file has 19 characters.
Line 2 sets the file’s absolute path. Line 3 reads the entire contents of
the file and saves the returned string in a variable named str using the
ReadContents() method. ReadContents() takes one argument: the pathname of
the file you want to read. Line 4 gets the length of the string and saves it in
a variable named len. Lines 5–6 display the str and len variables.
But why does GetLength() output 19 characters for the string’s length
when the string "This is a Test." contains only 15? To understand what’s
going on, you need to examine the actual characters that make up the
str variable. Remember from Chapter 18 that characters are encoded in a
format (such as ASCII or Unicode). Add the following code to the end of
Listing 19-1, and run the program again:
For N = 1 To len
ch = Text.GetSubText(str, N, 1) ' Gets one character
code = Text.GetCharacterCode(ch) ' Gets the code for this character
TextWindow.WriteLine(code) ' Displays it
EndFor
This code shows that the str variable has 19 characters. Figure 19-4
breaks down what the program is doing.
Code
84 104 105 115 13 10 105 115 32 97 13 10 13 10 84 101 115 116 46
Character
T
h i s i s a t e s t .
Carriage return
Line feed
Space
Carriage return
Line feed
Carriage return
Line feed
Figure 19-4: The 19 characters of the str variable in Listing 19-1
Notepad inserts two special characters (called carriage return and line
feed, whose ASCII codes are 13 and 10) to mark the end of each line. Think
of the newline (or end-of-line) marker as a pair of characters produced
when you press enter on the keyboard. Without these characters, the lines
292 Chapter 19