Versions - the version numbering scheme in curl
Version Numbers and Releases
Curl is not only curl. Curl is also libcurl. They're actually individually versioned, but they mostly follow each other rather closely.
The version numbering is always built up using the same system:
- X is main version number
- Y is release number
- Z is patch number
One of these numbers will get bumped in each new release. The numbers to the right of a bumped number will be reset to zero. If Z is zero, it may not be included in the version number.
The main version number will get bumped when really big, world colliding changes are made. The release number is bumped when changes are performed or things/features are added. The patch number is bumped when the changes are mere bugfixes.
It means that after release 1.2.3, we can release 2.0 if something really big has been made, 1.3 if not that big changes were made or 1.2.4 if mostly bugs were fixed.
Bumping, as in increasing the number with 1, is unconditionally only affecting one of the numbers (except the ones to the right of it, that may be set to zero). 1 becomes 2, 3 becomes 4, 9 becomes 10, 88 becomes 89 and 99 becomes 100. So, after 1.2.9 comes 1.2.10. After 3.99.3, 3.100 might come.
All original curl source release archives are named according to the libcurl version (not according to the curl client version that, as said before, might differ).
As a service to any application that might want to support new libcurl features while still being able to build with older versions, all releases have the libcurl version stored in the curl/curlver.h file using a static numbering scheme that can be used for comparison. The version number is defined as:
#define LIBCURL_VERSION_NUM 0xXXYYZZ
Where XX, YY and ZZ are the main version, release and patch numbers in hexadecimal. All three number fields are always represented using two digits (eight bits each). 1.2 would appear as "0x010200" while version 9.11.7 appears as "0x090b07".
This 6-digit hexadecimal number is always a greater number in a more recent release. It makes comparisons with greater than and less than work.
This number is also available as three separate defines: