Stepping through Collections in C#.NET

Create Code-39 in C#.NET Stepping through Collections

The DumpHex() method is a little tricky only because of the difficulties in formatting the output just right DumpHex() starts out by opening file A FileInfo object contains information about the file it doesn t open the file DumpHex() gets the full name of the file, including the path, and then opens a FileStream in read-only mode using that name The catch block throws an exception if FileStream can t read the file for some reason DumpHex() then reads through the file, 10 bytes at a time It displays every 10 bytes in hexadecimal format as a single line Every 20 lines, it pauses until the user presses Enter I use the modulo operator, %, to accomplish that task Vertically, a console window has room for 25 lines by default (The user can change the window s size, of course, allowing more or fewer lines) That means you have to pause every 20 lines or so Otherwise, the data just streams off the top of the screen before the user can read it The modulo operator (%) returns the remainder after division Thus (line % 20) == 0 is true when line equals 20, 40, 60, 80 you get the idea This trick is valuable, useful in all sorts of looping situations where you want to perform an operation only so often DumpBuffer() writes out each member of a byte array using the X2 format control Although X2 sounds like the name of a secret military experiment, it simply means display a number as two hexadecimal digits The range of a byte is 0 to 255, or 0xFF two hex digits per byte Here are the first 20 lines of the outputtxt file (even its own mother wouldn t recognize this picture):

Hex dump of file C:\C#ProgramsVi\holdtank\Test2\bin\outputtxt: 001 - 53, 74, 72, 65, 61, 6D, 20, 28, 70, 72, 002 - 6F, 74, 65, 63, 74, 65, 64, 29, 0D, 0A, 003 - 20, 20, 46, 69, 6C, 65, 53, 74, 72, 65, 004 - 61, 6D, 28, 73, 74, 72, 69, 6E, 67, 2C, 005 - 20, 46, 69, 6C, 65, 4D, 6F, 64, 65, 2C, 006 - 20, 46, 69, 6C, 65, 41, 63, 63, 65, 73, 007 - 73, 29, 0D, 0A, 20, 20, 4D, 65, 6D, 6F, 008 - 72, 79, 53, 74, 72, 65, 61, 6D, 28, 29, 009 - 3B, 0D, 0A, 20, 20, 4E, 65, 74, 77, 6F, 010 - 72, 6B, 53, 74, 72, 65, 61, 6D, 0D, 0A, 011 - 20, 20, 42, 75, 66, 66, 65, 72, 53, 74, 012 - 72, 65, 61, 6D, 20, 2D, 20, 62, 75, 66, 013 - 66, 65, 72, 73, 20, 61, 6E, 20, 65, 78, 014 - 69, 73, 74, 69, 6E, 67, 20, 73, 74, 72, 015 - 65, 61, 6D, 20, 6F, 62, 6A, 65, 63, 74, 016 - 0D, 0A, 0D, 0A, 42, 69, 6E, 61, 72, 79, 017 - 52, 65, 61, 64, 65, 72, 20, 2D, 20, 72, 018 - 65, 61, 64, 20, 69, 6E, 20, 76, 61, 72, 019 - 69, 6F, 75, 73, 20, 74, 79, 70, 65, 73, 020 - 20, 28, 43, 68, 61, 72, 2C, 20, 49, 6E, Enter return to continue another 20 lines

You could reconstruct the file as a string from the hex display The 0x61 value is the numeric equivalent of the character a The letters of the alphabet are arranged in order, so 0x65 should be the character e; 0x20 is a space The first line in this example (after the line number) is s)\n\r Nemo, where \n is a new line and \r is a carriage return Intriguing, eh That s about as far as I want to go You can search Google or another search engine for ASCII table Those codes are also valid for the lower part of the much vaster Unicode character set, which C# uses by default (You can look on a search engine on the Web for the term Unicode characters, and I explain the basics in the article Converting Between Byte and Char Arrays on the http:// csharp102info Web site) The following example shows what happens when the user specifies the invalid directory x:

Directory x invalid Could not find a part of the path C:\C#Programs\LoopThroughFiles\bin\Debug\x No files left Press Enter to terminate