Parsing version numbers to real numbers

Question

I would like to determine if one version number is greater than another. The version number could be any of the following:

4

4.2

4.22.2

4.2.2.233

...as the version number is beyond my control, so I couldn't say how many dots could actually exist in the number.

Since the number is not really a real number, I can't simply say,

Is 4.7 > 4.2.2

How can I go about converting a number, such as 4.2.2 into a real number that could be checked against another version number?

I would preferably like a ColdFusion solution, but the basic concept would also be fine.

Answer 1

This is ripped from the plugin update code in Mango Blog, and updated a little bit. It should do exactly what you want. It returns 1 when argument 1 is greater, -1 when argument 2 is greater, and 0 when they are exact matches. (Note that 4.0.1 will be an exact match to 4.0.1.0)

It uses the CF list functions, instead of arrays, so you might see a small performance increase if you switched to arrays instead... but hey, it works!

function versionCompare( version1, version2 ){
    var len1 = listLen(arguments.version1, '.');
    var len2 = listLen(arguments.version2, '.');
    var i = 0;
    var piece1 = '';
    var piece2 = '';

    if (len1 gt len2){
        arguments.version2 = arguments.version2 & repeatString('.0', len1-len2);
    }else if (len2 gt len1){
        arguments.version1 = arguments.version1 & repeatString('.0', len2-len1);
    }

    for (i=1; i lte listLen(arguments.version1, '.'); i=i+1){
        piece1 = listGetAt(arguments.version1, i, '.');
        piece2 = listGetAt(arguments.version2, i, '.');

        if (piece1 neq piece2){
            if (piece1 gt piece2){
                return 1;
            }else{
                return -1;
            }
        }
    }

    //equal
    return 0;
}

Running your example test:

<cfoutput>#versionCompare('4.7', '4.2.2')#</cfoutput>

prints:

1

Answer 2

If version 4 actually means 4.0.0, and version 4.2 actually means 4.2.0, you could easily convert the version to a simple integer.

suppose that every part of the version is between 0 and 99, then you could calculate an 'integer version' from X.Y.Z like this:

Version = X*100*100 + Y*100 + Z

If the ranges are bigger or smaller you could use factors higher or lower than 100.

Comparing the version then becomes easy.

Answer 3

Parse each number separately and compare them iteratively.

if (majorVersion > 4 &&
    minorVersion > 2 &&
    revision > 2)
{
    // do something useful
}

// fail here

That's obviously not CF code, but you get the idea.