Calculate gunning fog index in .Net

"Gunning fog" index is designed to measure the readability of English writing paragraphs. The result shows normally an estimate of the "number of years" of education he/she needs to understand the text on a first reading the text paragraph.

So here is the formula ...

Here is sample code to calculate gunning fog index written in VB.Net

//some variables

Dim inputText As String = txtInput.Text

Dim ltr As String

Dim wordCount As Integer

Dim sentenceCount As Integer

Dim syllableCount As Integer

Dim complexCount As Integer

Dim i As Integer

Dim inWord As Boolean = False

Dim vowels As String = "aeiouy"

TextBox1.Text = ""

' First make the input string case insensitive.

inputText = inputText.ToLower()

For i = 0 To inputText.Length() - 1

ltr = inputText.Substring(i, 1).ToLower

If ltr = "'" Then

   ' do nothing in case of apostrophe

ElseIf (ltr >= "a" And ltr <= "z") Then ' check for alphabetic input

If Not inWord Then ' new word

wordCount += 1 ' so add 1 to count

End If

inWord = True

Else ' could be space, full stop, comma etc

inWord = False ' no longer in word

' check if end of sentence

If (ltr = "." Or ltr = "?" Or ltr = "!" Or ltr = ":" Or ltr = ";") Then

sentenceCount += 1 ' add 1 to count

End If

End If

Next

Dim input As String = inputText.Length() - 1

Dim ch As Char

Dim inVowel As Boolean = False

' syllable count is zero if no input

If (input <>Then

syllableCount = 0

complexCount = 0

End If

' e at end of word doesn't count as a vowel

ch = inputText.Substring(inputText.Length - 1)

If (ch = "e") Then

input -= 1

End If

'For Each ch In inputText

' If (vowels.IndexOf(ch) >= 0) Then

' If Not inVowel Then

' syllableCount += 1

' End If

' inVowel = True

' End If

'Next

Dim word As String

Dim pieces As String()

'Replace all what is not needed here

inputText = inputText.Replace(".", " ")

inputText = inputText.Replace(":", " ")

inputText = inputText.Replace(";", " ")

inputText = inputText.Replace("?", " ")

inputText = inputText.Replace("!", " ")

inputText = inputText.Replace(",", "")

inputText = inputText.Replace("'", " ")

inputText = inputText.Replace(" ", " ")

'Now make pieces

pieces = inputText.Split(" ")

syllableCount = 0

complexCount = 0

For index As Integer = 0 To pieces.Length - 1

word = pieces(index)

word = word.ToLower().Trim()

Dim pattern As String = "[aeiouy]+"

'Handle vowels

Dim count As Integer = Regex.Matches(word, pattern).Count

If word.EndsWith("e") Then

count -= 1

End If

'some special cases

If word.EndsWith("cial") Or word.EndsWith("tia") Or word.EndsWith("cius") Or word.EndsWith("cious") Or word.EndsWith("giu") Or word.EndsWith("ion") Or word.EndsWith("iou") Then 'Or word.EndsWith("sia") Or word.EndsWith("ely") Then

count = 1

End If

syllableCount += count

If count <>Then

count = 1

End If

If count >= 3 Then

complexCount += 1

End If

Next

'Now display all results on GUI

TextBox1.Text += "Words: " & wordCount.ToString() & Environment.NewLine

TextBox1.Text += "Sentences: " & sentenceCount.ToString() & Environment.NewLine

TextBox1.Text += "Syllable: " & syllableCount.ToString() & Environment.NewLine

TextBox1.Text += "Complex Words: " & complexCount.ToString() & Environment.NewLine

TextBox1.Text += "Fog index: " & (0.4 * ((wordCount / sentenceCount) + (100 * (complexCount / wordCount)))).ToString() & Environment.NewLine

TextBox1.Text += "Flesch-Kincaid Reading Age: " & (206.876 - (1.015 * (wordCount / sentenceCount)) - (84.6 * (syllableCount / wordCount))).ToString() & Environment.NewLine