Version Number Ordering Systems
Version numbers very quickly evolve from simple integers (1, 2, ...) to rational numbers (2.08, 2.09, 2.10) and then to non-numeric "numbers" such as 4:3.4.3-2. These complex version numbers are therefore better treated as character strings. Operating systems that include package management facilities (such as all non-trivial Linux or BSD distributions) will use a distribution-specific algorithm for comparing version numbers of different software packages. For example, the ordering algorithms of Red Hat and derived distributions differ to those of the Debian-like distributions.
As an example of surprising version number ordering implementation behavior, in Debian, leading zeroes are ignored in chunks, so that 5.0005 and 5.5 are considered as equal, and 5.5<5.0006. This can confuse users; string-matching tools may fail to find a given version number; and this can cause subtle bugs in package management if the programmers use string-indexed data structures such as version-number indexed hash tables.
In order to ease sorting, some software packages will represent each component of the major.minor.release scheme with a fixed width. Perl represents its version numbers as a floating-point number, for example, Perl's 5.8.7 release can also be represented as 5.008007. This allows a theoretical version of 5.8.10 to be represented as 5.008010. Other software packages will pack each segment into a fixed bit width, for example, 5.8.7 could be represented in 24 bits: ( 5 << 16 | 8 << 8 | 7; hexadecimal: 050807; for version 12.34.56 in hexadecimal: 0C2238). The floating-point scheme will break down if any segment of the version number exceeds 1,000; a packed-binary scheme employing 8 bits apiece after 256.
Read more about this topic: Software Versioning
Famous quotes containing the words version, number, ordering and/or systems:
“Remember that you were a slave in the land of Egypt, and the LORD your God brought you out from there with a mighty hand and an outstretched arm; therefore the LORD your God commanded you to keep the sabbath day.”
—Bible: Hebrew, Deuteronomy 5:15.
See Exodus 22:8 for a different version of this fourth commandment.
“States strong enough to do good are but few.
Their number would seem limited to three.”
—Robert Frost (1874–1963)
“Seeing then that truth consisteth in the right ordering of names in our affirmations, a man that seeketh precise truth, had need to remember what every name he uses stands for; and to place it accordingly; or else he will find himself entangled in words, as a bird in lime-twigs; the more he struggles, the more belimed.”
—Thomas Hobbes (1579–1688)
“People stress the violence. That’s the smallest part of it. Football is brutal only from a distance. In the middle of it there’s a calm, a tranquility. The players accept pain. There’s a sense of order even at the end of a running play with bodies stewn everywhere. When the systems interlock, there’s a satisfaction to the game that can’t be duplicated. There’s a harmony.”
—Don Delillo (b. 1926)