How to Sort a Multi-Dimensional Array - A Quick Explanation of the Multi-Dimensional Array Function
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The function that I'll show you is built to handle multi-dimensional arrays and sort in an ascending fashion (least to greatest). Both of these can be changed.
The reason for handling multiple dimensions is simply that it happens many times those are the arrays we have and have to sort. Also, it's easier to handle the more complex issue of multiple dimensions in this tutorial, and let you dissect the function if you need to use it for a simple, one-dimensional array at any time.
Also, if you feel the need to sort things in descending order (greatest to least), you could also do that after dissecting the code. After I explain the full code, I'll explain how to do this; it just doesn't make a lot of sense to do it at this point!
Anyhow, without further delay, I will now move on to the function, what you've all come here to see.
The Code
Ok, so let's assume that we have an array that looks like this:
arEvents(0, 0) = 1
arEvents(1, 0) = "01-12-2004"
arEvents(2, 0) = "Event #1"
arEvents(0, 0) = 2
arEvents(1, 0) = "10-16-2004"
arEvents(2, 0) = "Event #2"
arEvents(0, 0) = 3
arEvents(1, 0) = "02-13-2004"
arEvents(2, 0) = "Event #3"
It could be sorted by simply handing it off to the arraySort() function, specifying which dimension to sort it by (in this case the date).
ArEvents = arraySort( arEvents, 1, true )
And then here's the function that's responsible for it all.
'==================================================
function arraySort( arToSort, sortBy, compareDates )
'==================================================
Dim c, d, e, smallestValue, smallestIndex, tempValue
For c = 0 To uBound( arToSort, 2 ) - 1
smallestValue = arToSort( sortBy, c )
smallestIndex = c
What's happening here is that we're going through the array one item at a time. With each item, we'll use the sortBy parameter, find the current item, and set the smallest value and index placeholders to the current item. Then we take these items, or placeholders, and compare them to EACH item in the array and look for a smaller value.
For d = c + 1 To uBound( arToSort, 2 )
if not compareDates then
So if the compareDates flag has been set to false, the function will try to compare the values as strings using the inbuilt strComp() function of ASP. Now, don't be too worried about numbers, they will be handled perfectly with this function as well. When we use the strComp() function, it will produce a -1 if the compared string (the first parameter) is smaller, a zero if they're equal, and a 1 if it's larger/greater. In this case, as we're sorting depending on smaller values, we would then set the placeholders to this value and index, if we find that it is indeed smaller. Now you're probably beginning to see where modifications could be made to sort in a descending order.
if strComp( arToSort( sortBy, d ), smallestValue ) < 0 Then
smallestValue = arToSort( sortBy, d )
smallestIndex = d
End if
else
So here we've got the code to handle dates, if the compareDates flag has been set to true. Of course we first check and ensure that we truly are dealing with dates. If not, we recurse, and come back through just comparing strings.
Next: And We Proceed with Our Checking >>
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