CBDL.exe is an interpreter for CBDL. It is written in C# and needs .NET 2.0. If you don't have .NET 2.0, please install it first. Here is procedure to get your program execute: 1. Write your program correctly & beautifully in Vietnamese :-). 2. If you want to see the result immediately, select menu item "Debug / Execute" in CBDLEditor. 3. If you want to run your app. without CBDLEditor, you can do one of the following: 3.1. Open cmd.exe, make sure CBDL.exe is in your search PATH, and invoke the command: "CBDL.exe your_file" this will execute your_file 3.2. Create a shell script ( a .bat file for DOS shell ) like this: @echo off C:\CBDL\CBDL.exe your_file.cbd once you have this shell script, you can just click on it and get your result, remember to include XuatNhap().DocDong(); at the last line in function BatDau, to make the console not disappear. Any bugs? ==> report to duc@nue.ci.i.u-tokyo.ac.jp. We're working for a fully Vietnamese programming language ( the keywords, program constructs, etc. are in Vietnamese with accents, as you see in normal Vietnamese textbook ). Suggestions, contributions are welcome!.