- Entry point
In
computer programming , an entry point is amemory address , corresponding to a point in the code of a computer program which is intended as destination of a long jump, be it internal or external.Usage customs
Contemporary
In most of today's popular computer systems, such as
Microsoft Windows andUnix , acomputer program usually only has a single entry point. In C andC++ programs this is themain()
function. Explicit internal long jumps are discouraged.Historical
Historically, and in some contemporary
legacy system s, such asVMS andOS/400 , computer programs have a multitude of entry points, each corresponding to the different functionalities of the program. The usual way to denote entry points, as used system-wide in VMS and inPL/I andMACRO programs, is to append them at the end of the name of theexecutable image , delimited by adollar sign ($) i.e.directory.exe$make
. The Apple 1 computer also used this to some degree. For example an alternative entry point in Apple 1 BASIC would keep the BASIC program, useful when the reset button was accidently pushed.
Wikimedia Foundation. 2010.