AND/AndAlso with Or/OrElse confusion
-1
I need to ensure the first item has a entry. (This is an import of a CSV file).
The intended action is if Item(471)).ToString is blank but there is a value >0 in either Item(475)).ToString) or Item(479)).ToString) alert that a date is required.
I have tried a few ways and cannot get this to work. If I take the OrElse statement out and use only one of the two it works. I am confused the proper syntax to get this to work. Can someone please point me in the correct direction?
If (MyList.Items.Item(471)).ToString = "" And CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
vb.net
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
add a comment |
-1
I need to ensure the first item has a entry. (This is an import of a CSV file).
The intended action is if Item(471)).ToString is blank but there is a value >0 in either Item(475)).ToString) or Item(479)).ToString) alert that a date is required.
I have tried a few ways and cannot get this to work. If I take the OrElse statement out and use only one of the two it works. I am confused the proper syntax to get this to work. Can someone please point me in the correct direction?
If (MyList.Items.Item(471)).ToString = "" And CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
vb.net
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
What's the confusion,AndAlso / OrElse'short circuit'?IF 1 = 0 And 1 = 1will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results.IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise withOr, which evaluates all conditions, even if first succeeds.OrElsecontinues forward only if it still needs to find a match. You might doIf ToyInBox("truck") OrElse ToyInPocket("truck"),ToyInPocket()is only checked ifToyInBox()is false
– Regular Joe
Nov 13 '18 at 21:05
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,ANDtakes precedence overORso you must use parentheses if you want anORoperator evaluated before anANDoperator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.
– jmcilhinney
Nov 14 '18 at 0:12
1
As for using choosing betweenAnd/OrandAndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS useAndAlso/OrElseunless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.
– jmcilhinney
Nov 14 '18 at 0:14
add a comment |
-1
-1
-1
I need to ensure the first item has a entry. (This is an import of a CSV file).
The intended action is if Item(471)).ToString is blank but there is a value >0 in either Item(475)).ToString) or Item(479)).ToString) alert that a date is required.
I have tried a few ways and cannot get this to work. If I take the OrElse statement out and use only one of the two it works. I am confused the proper syntax to get this to work. Can someone please point me in the correct direction?
If (MyList.Items.Item(471)).ToString = "" And CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
vb.net
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
I need to ensure the first item has a entry. (This is an import of a CSV file).
The intended action is if Item(471)).ToString is blank but there is a value >0 in either Item(475)).ToString) or Item(479)).ToString) alert that a date is required.
I have tried a few ways and cannot get this to work. If I take the OrElse statement out and use only one of the two it works. I am confused the proper syntax to get this to work. Can someone please point me in the correct direction?
If (MyList.Items.Item(471)).ToString = "" And CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
vb.net
vb.net
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
asked Nov 13 '18 at 20:49
John EtlingJohn Etling
17
17
What's the confusion,AndAlso / OrElse'short circuit'?IF 1 = 0 And 1 = 1will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results.IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise withOr, which evaluates all conditions, even if first succeeds.OrElsecontinues forward only if it still needs to find a match. You might doIf ToyInBox("truck") OrElse ToyInPocket("truck"),ToyInPocket()is only checked ifToyInBox()is false
– Regular Joe
Nov 13 '18 at 21:05
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,ANDtakes precedence overORso you must use parentheses if you want anORoperator evaluated before anANDoperator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.
– jmcilhinney
Nov 14 '18 at 0:12
1
As for using choosing betweenAnd/OrandAndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS useAndAlso/OrElseunless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.
– jmcilhinney
Nov 14 '18 at 0:14
add a comment |
What's the confusion,AndAlso / OrElse'short circuit'?IF 1 = 0 And 1 = 1will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results.IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise withOr, which evaluates all conditions, even if first succeeds.OrElsecontinues forward only if it still needs to find a match. You might doIf ToyInBox("truck") OrElse ToyInPocket("truck"),ToyInPocket()is only checked ifToyInBox()is false
– Regular Joe
Nov 13 '18 at 21:05
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,ANDtakes precedence overORso you must use parentheses if you want anORoperator evaluated before anANDoperator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.
– jmcilhinney
Nov 14 '18 at 0:12
1
As for using choosing betweenAnd/OrandAndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS useAndAlso/OrElseunless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.
– jmcilhinney
Nov 14 '18 at 0:14
What's the confusion,
AndAlso / OrElse 'short circuit'? IF 1 = 0 And 1 = 1 will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results. IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise with Or, which evaluates all conditions, even if first succeeds. OrElse continues forward only if it still needs to find a match. You might do If ToyInBox("truck") OrElse ToyInPocket("truck"), ToyInPocket() is only checked if ToyInBox() is false– Regular Joe
Nov 13 '18 at 21:05
What's the confusion,
AndAlso / OrElse 'short circuit'? IF 1 = 0 And 1 = 1 will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results. IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise with Or, which evaluates all conditions, even if first succeeds. OrElse continues forward only if it still needs to find a match. You might do If ToyInBox("truck") OrElse ToyInPocket("truck"), ToyInPocket() is only checked if ToyInBox() is false– Regular Joe
Nov 13 '18 at 21:05
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,
AND takes precedence over OR so you must use parentheses if you want an OR operator evaluated before an AND operator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.– jmcilhinney
Nov 14 '18 at 0:12
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,
AND takes precedence over OR so you must use parentheses if you want an OR operator evaluated before an AND operator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.– jmcilhinney
Nov 14 '18 at 0:12
1
1
As for using choosing between
And/Or and AndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS use AndAlso/OrElse unless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.– jmcilhinney
Nov 14 '18 at 0:14
As for using choosing between
And/Or and AndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS use AndAlso/OrElse unless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.– jmcilhinney
Nov 14 '18 at 0:14
add a comment |
1 Answer
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-1
If (MyList.Items.Item(471)).ToString = "" AndAlso (CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D) Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
In short
If condition1 AndAlso (condition2 OrElse condition3) Then
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
add a comment |
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1 Answer
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-1
If (MyList.Items.Item(471)).ToString = "" AndAlso (CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D) Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
In short
If condition1 AndAlso (condition2 OrElse condition3) Then
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
add a comment |
-1
If (MyList.Items.Item(471)).ToString = "" AndAlso (CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D) Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
In short
If condition1 AndAlso (condition2 OrElse condition3) Then
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
add a comment |
-1
-1
-1
If (MyList.Items.Item(471)).ToString = "" AndAlso (CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D) Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
In short
If condition1 AndAlso (condition2 OrElse condition3) Then
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
If (MyList.Items.Item(471)).ToString = "" AndAlso (CDec((MyList.Items.Item(475)).ToString) > 0D OrElse CDec((MyList.Items.Item(479)).ToString) > 0D) Then
MessageBox.Show("FUELING DATE #1 CANNOT BE BLANK", "Critical Warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
Else
tbDate1.Text = (MyList.Items.Item(471)).ToString
End If
In short
If condition1 AndAlso (condition2 OrElse condition3) Then
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
answered Nov 13 '18 at 20:54
Martin S.Martin S.
666
666
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
add a comment |
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
My overall error was that I had forgotten I needed Parenthesis around my OrElse statement. Thanks for the help.
– John Etling
Nov 15 '18 at 6:28
add a comment |
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What's the confusion,
AndAlso / OrElse'short circuit'?IF 1 = 0 And 1 = 1will evaluate both conditions, even though it knows the first condition isn't true. In cases where a function is in your if-line, this can lead to unexpected results.IF 1 = 0 AndAlso 1 = 1" checks 1 = 0, evaluates to false, and ditches the if-branch. Likewise withOr, which evaluates all conditions, even if first succeeds.OrElsecontinues forward only if it still needs to find a match. You might doIf ToyInBox("truck") OrElse ToyInPocket("truck"),ToyInPocket()is only checked ifToyInBox()is false– Regular Joe
Nov 13 '18 at 21:05
If you're confused, it's because you didn't listen well enough in maths class when taught about operator precedence. In Boolean logic,
ANDtakes precedence overORso you must use parentheses if you want anORoperator evaluated before anANDoperator. It's exactly the same situation us using parentheses to for an addition to be evaluated before a multiplication in a basic arithmetic expression.– jmcilhinney
Nov 14 '18 at 0:12
1
As for using choosing between
And/OrandAndAlso/OrElse, that's irrelevant to this question. Either would work in this particular case but you should always work by the following rule: ALWAYS useAndAlso/OrElseunless you specifically don't want short-circuiting and, if you don't want short-circuiting then you probably ought to rethink your design to avoid it.– jmcilhinney
Nov 14 '18 at 0:14