How Do I Write A Linq Statement That Will Turn A Letter Into An Integer

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I am trying to write a linq statement that will change the letter of a grade into a number so i can calculate gpa.
Can anyone tell me what is wrong with the below code sinnpet.

How and where can I declare the word grade so i can stop getting the error grade is not declared?

VB

Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click
        Dim Gpa As String = Aggregate CreditHours In CoursesDataSet.tblCourses
                           Let gradeValue = If(Grade = "A", 4, If(Grade = "B", 3, If(Grade = "C", 2, If(Grade = "D", 1, 0))))
                           Select CreditHours * gradeValue
                           Into Sum()



        MessageBox.Show("GPa:" & Gpa.ToString("C2"),
                       "College Courses", MessageBoxButtons.OK,
 MessageBoxIcon.Information)


    End Sub

Posted 4-May-15 10:50am

karodhill

Updated 5-May-15 9:36am

Liju Sankar

v2

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Maciej Los 5-May-15 14:18pm

http://stackoverflow.com/questions/30034330/linq-statement-error/30035184

2 solutions

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Maciej Los · Answer 1 · 2015-05-06T20:39:00

Solution 2

Actually, you've got your answer here: http://stackoverflow.com/questions/30034330/linq-statement-error/30035184[^]

Posted 6-May-15 20:39pm

Maciej Los

Ralf Meier · Answer 2 · 2015-05-05T07:19:00

Solution 1

Hi,
you could use the ASCII-Code of the Character.
For Example :

VB

dim myInt as integer = ASC(Grade)

In this Example myInt will have 65 for "A", 66 for "B" and so on.
But Attention : the ASCII-Code for Uppercase and Lowercase is not the same !

Greetings
Ralf

Posted 5-May-15 7:19am

Ralf Meier

Comments

karodhill 7-May-15 11:06am

i was thinking of a more simpler where clause i tried to do it this way

but i get an error
for the grades saying option strict on disallows implicit conversions from
string to boolean

Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click

<pre>
Dim dic As Dictionary(Of String, Integer) = New Dictionary(Of String, Integer)
dic.Add("A", 4)
dic.Add("B", 3)
dic.Add("C", 2)
dic.Add("D", 1)
dic.Add("F", 0)

Dim gpa = Aggregate Grade In CoursesDataSet.tblCourses.AsEnumerable()
Where Grade.Grade = "A" Or "B" Or "C" Or "D" Or "F"
Select Grade.Field(Of Integer)("CreditHours") * dic(Grade.Field(Of String)("Grade"))
Into Sum()</pre>