Programming .NET Windows Applications

Text

Text can be thought of as the output from a typewriter (remember typewriters?). That is, text is just characters, with no special formatting other than spaces, tabs, and newlines. Text is typically saved to a file (often called a flat file or an ASCII file).

On most Windows systems, text files commonly (but not always) have the file extension .txt. Double-click on a file with that extension in Windows Explorer, and Notepad, the default application for .txt files, will open. .NET programs can capture text in String objects.

In a single-byte character set, each text character is defined by one byte of data. The maximum one byte number in hexadecimal is FF, or 255 in decimal. Thus, using a zero-based index, a maximum of 256 different characters can be represented in a single byte character set, since each character must be uniquely indexed. The index assigned to a character is called the code point or character code.

The most commonly used single byte character set in the PC world is the American Standards Committee for Information Interchange (ASCII) character set. The first 128 characters, corresponding to seven bit bytes (maximum hex value of 7F), are more or less standardized and are usually considered low-order ASCII characters. The upper 128 characters are not part of the ASCII standard, although many well established character sets use all 256 characters.

Tip

The mainframe world often uses a similar, but incompatible, single byte character set called Extended Binary Coded Decimal ...