optimal code for detecting formatting differences?

Question

I need to compare two formatted strings. The text in the two of them is the same, only the formatting differs, meaning that some words are bold. The code should tell me if the location of the bold substrings are different e.g. the strings are formatted differently. So far I tried a char-to-char approach, but it is far too slow.

It's a plain legal current text in MS Word, with cca 10-500 chars per string. Two people independently formatted the strings.

my code so far:

Function collectBold(r As Range) As String
Dim chpos As Integer
Dim ch As Variant
Dim str, strTemp As String
chpos = 1
Do
If r.Characters(chpos).Font.Bold Then
    Do
        Dim boold As Boolean
        strTemp = strTemp + r.Characters(chpos)
        chpos = chpos + 1
        If (chpos < r.Characters.Count) Then boold = r.Characters(chpos).Font.Bold
    Loop While (boold And chpos < r.Characters.Count)
   str = str + Trim(strTemp) + "/"
   strTemp = ""
Else: chpos = chpos + 1
End If
Loop While (chpos < r.Characters.Count)
collectBold = str
End Function

This code collect all bold substrings (strTemp) and merges them into one string (str), separating them with "/". The function runs for both strings to compare, and then checks if the outputs are the same.

Answer 1

If you only need to see if they are different, this function will do it:

Function areStringsDifferent(range1 As Range, range2 As Range) As Boolean
    Dim i As Integer, j As Integer

    For i = 1 To range1.Words.Count
        'check if words are different formatted
        If Not range1.Words(i).Bold = range2.Words(i).Bold Then
            areStringsDifferent = True
            Exit Function
        'words same formatted, but characters may not be
        ElseIf range1.Words(i).Bold = wdUndefined Then
            For j = 1 To range1.Words(i).Characters.Count
                If Not range1.Words(i).Characters(j).Bold = range2.Words(i).Characters(j).Bold Then
                    areStringsDifferent = True
                    Exit Function
                End If
            Next
        End If
    Next

    areStringsDifferent = False
End Function

It first looks if the words are different formatted... If they have the same format but the format is undefinied, it looks into the characters of the word.