On the Facebook Developers site, Haiping Zhao writes about how Facebook uses HipHop to transform PHP code to C++ and compiles them using g++. In his article titled, HipHop for PHP: Move Fast, he mentions:

HipHop for PHP isn’t technically a compiler itself. Rather it is a source code transformer. HipHop programmatically transforms your PHP source code into highly optimized C++ and then uses g++ to compile it. HipHop executes the source code in a semantically equivalent manner and sacrifices some rarely used features — such as eval() — in exchange for improved performance. HipHop includes a code transformer, a reimplementation of PHP’s runtime system, and a rewrite of many common PHP Extensions to take advantage of these performance optimizations.

In his article he describes how this tool helps to allow Facebook to scale to millions of users. He also mentions that HipHop has been released using the open source PHP license.

To display line numbers in code

1. On the Tools menu selecti, Options.
2. In the Text Editor folder, choose the General options in the All Languages subfolder to set this option globally
3. Under Display, select Line numbers.

If you do not see the All Languages subfolder or the Display section, make sure that the Show all settings checkbox at the bottom of the window is checked.

Reference

When requiring the user to enter only positive numbers (integer, double, currency) within a specified limit, you do not need to have both a RegularExpressionValidator to check for positive values and a RangeValidator to provide a limit. You can just use the RangeValidator and just set the Minimum property to 0. (Visual Web Developer Express 2008 and .NET 3.5)