Notepad++ is a free source code editor (and Notepad replacement), which supports several programming languages, running under the MS Windows environment. This project, based on the Scintilla edit component (a very powerful editor component), written in C++ with pure win32 api and STL (that ensures the higher execution speed and smaller size of the program), is under the GPL Licence.Here are the features of Notepad++ :

Syntax Highlighting and Syntax Folding

Supported languages : C, C++, Java, C#, XML, HTML, PHP, Javascript, RC resource file, makefile, ASCII art file (extension .nfo , screenshot1, screenshot2), doxygen, ini file, batch file, ASP, VB/VBS source files, SQL, Objective-C,
CSS, Pascal, Perl, Python, Lua, TeX, TCL, Assembler, Ruby, Lisp,
Scheme, Properties, Diff, Smalltalk, Postscript, VHDL, Ada, Caml,
AutoIt, KiXtart, Matlab, Verilog, Haskell and InnoSetup.

WYSIWYG

If you have a colour printer, print your source code (or whatever you want) in colour.

User Defined Syntax Highlighting

It allows user to define his own language : not only the syntax
highlighting keywords, but also the syntax folding keywords, comment
keywords and the operators. ( screenshot1,
screenshot2,
screenshot3,
screenshot4
).

Auto-completion

For most supported languages, user can make his/her own API list (or download the api files from dowload section). Once the api file is ready, type Ctrl+Space to launch this action (see screenshot). For more information about Auto-completion, please see Auto-completion HOWTO.

Multi-Document

You can edit several documents at the same time.

Multi-View

You have two views at same time. That means you can visualize (edit) 2 different documents at the same time
(screenshot).
You can visualize (edit) in the 2 views one document at 2 different
positions as well. The modification of document in one view will carry
out in another view (i.e. you modify the SAME document when you are in
clone mode, see screenshot).

Regular Expression Search/Replace supported

You can search and replace one string in the document by using the regular expression.

Full Drag ‘N' Drop supported

You can open a document by drag & drop. You can also move your
document from a position (or even a view) to another by drag &
drop.

Dynamic position of Views

The user can set the position of the views dynamically (only in 2 views
mode : the splitter can be set in horizontal or in vertical), see screenshot.

File Status Auto-detection

If you modify or delete a file which opened in Notepad++, you will be
notified to update your document (reload the file or remove the file).

Zoom in and zoom out

That's another fantastic function of Scintilla component. Just see screenshot.

Multi-Language environment supported

The Chinese, Japanese, Korean, Arabic and Hebrew Windows environments are supported. See Notepad++ under the Chinese Windows
, under the Arabic Windows and under the Hebrew Windows
in action screenshot.

Bookmark

User can just click on the bookmark margin (located right side of line number margin) or type Ctrl+F2 to toggle a book mark. To reach the bookmark, type just F2 (Next bookmark) or Shift+F2 (Previous bookmark). To clear all bookmarks, click the Menu Search->Clear All bookmarks. See screenshot.

Brace and Indent guideline Highlighting

When the caret stay beside of one of those symbol { } [ ] ( )
, the symbol beside of caret and its symmetric opposite symbol will be
highlighted, as well as the indent guideline (if any) in order to
locate the block more easily. See screenshot1, screenshot2 .

Macro recording and playback