Operator (-) is not defined for types 'char' and integer

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hello, i have some codes in c# which i converted in vb then it throws this error saying

operator (-) is not defined for types 'char' and integer

and it works fine in c#.

here's the c# code and vb code

else if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f'))
                {
                    // get the character's value
                    byte v = (byte)(c - 0x30);
                    if (c >= 'A' && c <= 'F') v = (byte)(c + 0x0a - 'A');
                    if (c >= 'a' && c <= 'f') v = (byte)(c + 0x0a - 'a');

                    if (gotFirstChar == false)
                    {
                        gotFirstChar = true;
                        accum = v;
                    }

in the vb this is the converted code

ElseIf (c >= "0"c AndAlso c <= "9"c) OrElse (c >= "A"c AndAlso c <= "F"c) OrElse (c >= "a"c AndAlso c <= "f"c) Then
                   ' get the character's value
                   Dim v As Byte = CByte(c - &H30)
                   If c >= "A"c AndAlso c <= "F"c Then
                       v = CByte(c + &HA - "A"c)
                   End If
                   If c >= "a"c AndAlso c <= "f"c Then
                       v = CByte(c + &HA - "a"c)
                   End If

                   If gotFirstChar = False Then
                       gotFirstChar = True
                       accum = v

What I have tried:

ElseIf (c >= "0"c AndAlso c <= "9"c) OrElse (c >= "A"c AndAlso c <= "F"c) OrElse (c >= "a"c AndAlso c <= "f"c) Then
                   ' get the character's value
                   Dim v As Byte = CByte(c - &H30)
                   If c >= "A"c AndAlso c <= "F"c Then
                       v = CByte(c + &HA - "A"c)
                   End If
                   If c >= "a"c AndAlso c <= "f"c Then
                       v = CByte(c + &HA - "a"c)
                   End If

                   If gotFirstChar = False Then
                       gotFirstChar = True
                       accum = v

Posted 12-Mar-17 12:14pm

Member 11721323

Updated 13-Mar-17 3:56am

Jochen Arndt

v2

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Jochen Arndt 13-Mar-17 4:42am

I have edited the question because the whole page view was messed up by some HTML tags in the "What have I tried" section.

2 solutions

Solution 1

Hi Member 11721323,

Rather than using "A"c, "a"c etc., use Asc("A").

E.g.:

ElseIf (c >= Asc("0") AndAlso c <= Asc("9")) OrElse ......................
.........................................................................

This is because in C# character types are automatically casted implicitly, in VB.NET an explicit cast (conversion, to be precise) is required. Asc converts the character to its ASCII equivalent.

Posted 12-Mar-17 12:31pm

Mehedi Shams

Comments

Richard MacCutchan 13-Mar-17 4:27am

There is no need to use bold text in your replies.

Jochen Arndt 13-Mar-17 4:39am

This was caused by some HTML tags in the question itself which messed up the whole page view (and blended out some code).

Richard MacCutchan 13-Mar-17 4:44am

Thanks, I should have looked more closely.

Member 11721323 13-Mar-17 9:20am

have tried what you said MR mehedi shams, but it still returns error saying operator (<=) is not defined for types 'char' and integer

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F. Xaver · Accepted Answer · 2017-03-13T03:56:00

That <= etc operations aren't your problem those work fine with char. (Solution 1)

VB

CByte(c + &HA - "A"c)

This is your problem.. you try to calculate something of type Char with an Integer.
I wonder what are you trying to archive anyway? be course.. for getting the Integer of an HEX .. there are already .Net functions

VB

Dim i As Integer = Integer.Parse("12FF", Globalization.NumberStyles.HexNumber)

i => 4863