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Why Won't This "Select Case" Work?
The following Select Case will always goes to Case Else. "a" is always what it was before the Case is executed. "a" is a Decimal. "b" is an Object.
Select Case a
Case a >= 100
b.Image = Change_Calculator.My.Resources.Resources.hundred
a = a - 100
Case a >= 50
b.Image = Change_Calculator.My.Resources.Resources.fifty
a = a - 50
Case a >= 20
b.Image = Change_Calculator.My.Resources.Resources.twenty
a = a - 20
Case a >= 10
b.Image = Change_Calculator.My.Resources.Resources.ten
a = a - 10
Case a >= 5
b.Image = Change_Calculator.My.Resources.Resources.five
a = a - 5
Case a >= 1
b.Image = Change_Calculator.My.Resources.Resources.one
a = a - 1
Case a >= 0.25
b.Image = Change_Calculator.My.Resources.Resources.quarter
a = a - 0.25
Case a >= 0.1
b.Image = Change_Calculator.My.Resources.Resources.dime
a = a - 0.1
Case a >= 0.05
b.Image = Change_Calculator.My.Resources.Resources.nickel
a = a - 0.05
Case a >= 0.01
b.Image = Change_Calculator.My.Resources.Resources.penny
a = a - 0.01
Case Else
MessageBox.Show("Case Else on Select Case a. ""a"" is currently: " & a)
End
End Select
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As I said above^
Limitations of Select Case:
The Select Case statement only allows you to check if a variable is equal to a value - you can't test to see if it is greater than, less than etc. Also, you can only test against one variable. If you have multiple variables to test against, you'll need to use an If statement.
Limitations of Select Case:
The Select Case statement only allows you to check if a variable is equal to a value - you can't test to see if it is greater than, less than etc. Also, you can only test against one variable. If you have multiple variables to test against, you'll need to use an If statement.
@ dstewartjr;
The link you posted was information on VBScript which is different then Visual Basic .Net 2005.
From Microsoft documentation - Select...Case Statement (Visual Basic):
expressionlist
Required in a Case statement. List of expression clauses representing match values for testexpression. Multiple expression clauses are separated by commas. Each clause can take one of the following forms:
expression1 To expression2
[ Is ] comparisonoperator expression
expression
Use the To keyword to specify the boundaries of a range of match values for testexpression. The value of expression1 must be less than or equal to the value of expression2.
Use the Is keyword with a comparison operator (=, <>, <, <=, >, or >=) to specify a restriction on the match values for testexpression. If the Is keyword is not supplied, it is automatically inserted before comparisonoperator.
The form specifying only expression is treated as a special case of the Is form where comparisonoperator is the equal sign (=). This form is evaluated as testexpression = expression.
The expressions in expressionlist can be of any data type, provided they are implicitly convertible to the type of testexpression and the appropriate comparisonoperator is valid for the two types it is being used with.
http://msdn.microsoft.com/en-us/library/cy37t14y.aspx
Fernando
The link you posted was information on VBScript which is different then Visual Basic .Net 2005.
From Microsoft documentation - Select...Case Statement (Visual Basic):
expressionlist
Required in a Case statement. List of expression clauses representing match values for testexpression. Multiple expression clauses are separated by commas. Each clause can take one of the following forms:
expression1 To expression2
[ Is ] comparisonoperator expression
expression
Use the To keyword to specify the boundaries of a range of match values for testexpression. The value of expression1 must be less than or equal to the value of expression2.
Use the Is keyword with a comparison operator (=, <>, <, <=, >, or >=) to specify a restriction on the match values for testexpression. If the Is keyword is not supplied, it is automatically inserted before comparisonoperator.
The form specifying only expression is treated as a special case of the Is form where comparisonoperator is the equal sign (=). This form is evaluated as testexpression = expression.
The expressions in expressionlist can be of any data type, provided they are implicitly convertible to the type of testexpression and the appropriate comparisonoperator is valid for the two types it is being used with.
http://msdn.microsoft.com/en-us/library/cy37t14y.aspx
Fernando
My bad :D)
I'll have to remember this.
I'll have to remember this.
Not a problem.
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@ VK;
How is the solution you posted more flexible then the one I posted?
Fernando
How is the solution you posted more flexible then the one I posted?
Fernando
It is more flexible e. g. in the case below:
Public Function Str2Lng(Text As String, Optional Default As Long) As Long
Select Case True
Case IsNumeric(Text)
Str2Lng = CLng(Text)
Case Else
Select Case Val(Text)
Case 0
Str2Lng = Default
Case Else
Str2Lng = CLng(Val(Text))
End Select
End Select
End Function
Public Function Str2Lng(Text As String, Optional Default As Long) As Long
Select Case True
Case IsNumeric(Text)
Str2Lng = CLng(Text)
Case Else
Select Case Val(Text)
Case 0
Str2Lng = Default
Case Else
Str2Lng = CLng(Val(Text))
End Select
End Select
End Function
or another case:
Select Case True
Case a > 0, b > 0
Case a > 0
Case b > 0
Case Else
End Select
Select Case True
Case a > 0, b > 0
Case a > 0
Case b > 0
Case Else
End Select
@ VK;
Do you have a link to a technical specification that explains why one is more flexible then the other? I do not see any reason why in these example that would be so.
Do you have a link to a technical specification that explains why one is more flexible then the other? I do not see any reason why in these example that would be so.
It is moe flexible because of the "True" in "Select Case True".
If you have a variable instead of "true" you are restricted to
copmpare with the <<one>> variable.
With "Select Case True" you have a real replacement for the often used and bad
coding practice "elseif".
If you have a variable instead of "true" you are restricted to
copmpare with the <<one>> variable.
With "Select Case True" you have a real replacement for the often used and bad
coding practice "elseif".
If a Then
Else
End If
can be replaced with
Select Case True
Case a
Case Else
End Select
The "Select Case True"-constuct is a superset of the if and the elseif-statements.
Else
End If
can be replaced with
Select Case True
Case a
Case Else
End Select
The "Select Case True"-constuct is a superset of the if and the elseif-statements.
Assuming vb6-language wouldn't have any if and elseif and iif-statements,
you wouldn't have any significant restrictions by using the "select case" statement.
In the inverse case it would be very inconvenient to replace the "select case"-statement.
you wouldn't have any significant restrictions by using the "select case" statement.
In the inverse case it would be very inconvenient to replace the "select case"-statement.
ASKER
Thanks for the help guys! That worked perfectly.
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When you need to check for many different cases on one variable you could create a large number of ElseIf statements, but this is actually very inefficient. Without getting to specific, it takes VBScript a great deal of computing power to check all these different ElseIf statements. Also, this kind of coding reduces human readability. Because of these problems another programming method, the Select Case statement, was created to solve this problem. The downside to this new method is you can only check if a variable is equal to something "=" and not compare it with greater than, less than, etc (>, <, >=, <=).