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VersionStrings

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README

VersionStrings.pp

Author

Bill Stewart (bstewart AT iname.com)

License

VersionStrings.pp is covered by the GNU Lesser Public License (LPGL). See the file LICENSE for details.

Description

VersionStrings.pp is a Free Pascal (FPC) unit for checking the validity of and comparing version numbers in string format.

Reference

This section documents the functions in the unit.

A version number string uses the following format:

a[.b[.c[.d]]]

Where a, b, c, and d are values from 0 to 65535, inclusive, separated by dots. Parts b, c, and d are optional and are assumed to be 0 if not specified. The following are examples of valid version strings:

  • 10 - same as 10.0.0.0
  • 10.3 - same as 10.3.0.0
  • 10.3.251 - same as 10.3.251.0
  • 10.4.2500.32124

A string that does not conform to the above rules is not a valid version string. The following are examples of version strings that are not valid:

  • 10.65536 - contains a part greater than 65535
  • -3 - negative values not allowed
  • 10,3 - string contains characters other than numbers or dots

TestVersionString

Tests whether a specified version string is valid. See above for a description of a valid version string.

Syntax

pascal
function TestVersionString(const VersionString: UnicodeString): Boolean;

Parameters

VersionString - Specifies the version string to test for validity.

Return Value

The function returns true if the version string is valid, or false otherwise.

CompareVersionStrings

Compares two version strings.

Syntax

pascal
function CompareVersionStrings(const VersionString1, VersionString2: UnicodeString): Integer;

Parameters

VersionString1 - Specifies a version string to compare.

VersionString2 - Specifies a version string to compare.

Return Value

The return value will be less than 0 if VersionString1 is less than VersionString2, 0 if VersionString1 is equal to VersionString2, or greater than 0 if VersionString1 is greater than VersionString2.

The return value will be 0 if either version string is not a valid version string, so it is recommended to validate both VersionString1 and VersionString2 before relying on the return value from this function.

Examples

See the following table for return value examples:

Expression Return Value
CompareVersionStrings('10', '10.0') 0
CompareVersionStrings('1.10', '1.09') > 0
CompareVersionStrings('2.3.0', '2.5') < 0