I get an error about an "unresolved external symbol _main"!

Description

I get an error about an "unresolved external symbol _main"!
Make sure you're building a Windows GUI Application, and not a Windows Console Application. This is a setting when you create the project in MSVC, Dev-C++ or Borland C++ Builder. Alternatively, this is specified on the command line by the -subsystem:windows option for the MSVC linker, by the -Wl,--subsystem,windows option for the MinGW compiler or the -tW option for the Borland C++ compiler. Either that, or define the preprocessor symbol ALLEGRO_USE_CONSOLE prior to including Allegro headers if you really need the console for your program.