Mixing
VB.net: “Input string was not in a correct format.” Using Convert.ToDouble
-1
I keep receiving the error mention in the title. I've tried replacing all "+" with "&" as mentioned in other threads, but it doesn't seem to work. I wanted to create a program that allows me to see my weight on other planets using VB.net but I cannot get past this "Input string was not in a correct format" error. Any help please? The error occurs at the first line.
Convert.ToDouble(ComboBox1.SelectedItem())
If ComboBox1.SelectedItem = 0 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.378)
ElseIf ComboBox1.SelectedItem = 1 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.905)
ElseIf ComboBox1.SelectedItem = 2 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.0)
ElseIf ComboBox1.SelectedItem = 3 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.379)
ElseIf ComboBox1.SelectedItem = 4 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 2.529)
ElseIf ComboBox1.SelectedItem = 5 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.066)
ElseIf ComboBox1.SelectedItem = 6 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.903)
ElseIf ComboBox1.SelectedItem = 7 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.096)
ElseIf ComboBox1.SelectedItem = 8 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.069)
End If
vb.net
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
|
show 1 more comment
-1
I keep receiving the error mention in the title. I've tried replacing all "+" with "&" as mentioned in other threads, but it doesn't seem to work. I wanted to create a program that allows me to see my weight on other planets using VB.net but I cannot get past this "Input string was not in a correct format" error. Any help please? The error occurs at the first line.
Convert.ToDouble(ComboBox1.SelectedItem())
If ComboBox1.SelectedItem = 0 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.378)
ElseIf ComboBox1.SelectedItem = 1 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.905)
ElseIf ComboBox1.SelectedItem = 2 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.0)
ElseIf ComboBox1.SelectedItem = 3 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.379)
ElseIf ComboBox1.SelectedItem = 4 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 2.529)
ElseIf ComboBox1.SelectedItem = 5 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.066)
ElseIf ComboBox1.SelectedItem = 6 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.903)
ElseIf ComboBox1.SelectedItem = 7 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.096)
ElseIf ComboBox1.SelectedItem = 8 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.069)
End If
vb.net
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
2
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
Do you mean.SelectedIndex? The.Textproperty of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.
– Mary
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Looks like you intended to check the value ofSelectedIndex, not theSelectedItem?
– Ahmed Abdelhameed
Nov 20 '18 at 20:51
|
show 1 more comment
-1
-1
-1
I keep receiving the error mention in the title. I've tried replacing all "+" with "&" as mentioned in other threads, but it doesn't seem to work. I wanted to create a program that allows me to see my weight on other planets using VB.net but I cannot get past this "Input string was not in a correct format" error. Any help please? The error occurs at the first line.
Convert.ToDouble(ComboBox1.SelectedItem())
If ComboBox1.SelectedItem = 0 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.378)
ElseIf ComboBox1.SelectedItem = 1 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.905)
ElseIf ComboBox1.SelectedItem = 2 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.0)
ElseIf ComboBox1.SelectedItem = 3 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.379)
ElseIf ComboBox1.SelectedItem = 4 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 2.529)
ElseIf ComboBox1.SelectedItem = 5 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.066)
ElseIf ComboBox1.SelectedItem = 6 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.903)
ElseIf ComboBox1.SelectedItem = 7 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.096)
ElseIf ComboBox1.SelectedItem = 8 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.069)
End If
vb.net
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
I keep receiving the error mention in the title. I've tried replacing all "+" with "&" as mentioned in other threads, but it doesn't seem to work. I wanted to create a program that allows me to see my weight on other planets using VB.net but I cannot get past this "Input string was not in a correct format" error. Any help please? The error occurs at the first line.
Convert.ToDouble(ComboBox1.SelectedItem())
If ComboBox1.SelectedItem = 0 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.378)
ElseIf ComboBox1.SelectedItem = 1 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.905)
ElseIf ComboBox1.SelectedItem = 2 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.0)
ElseIf ComboBox1.SelectedItem = 3 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.379)
ElseIf ComboBox1.SelectedItem = 4 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 2.529)
ElseIf ComboBox1.SelectedItem = 5 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.066)
ElseIf ComboBox1.SelectedItem = 6 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.903)
ElseIf ComboBox1.SelectedItem = 7 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 1.096)
ElseIf ComboBox1.SelectedItem = 8 Then
Label4.Text = "Your weight on " + ComboBox1.SelectedItem() + " is " + (TextBox1.Text * 0.069)
End If
vb.net
vb.net
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
asked Nov 20 '18 at 20:39
surrealismsurrealism
1
1
2
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
Do you mean.SelectedIndex? The.Textproperty of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.
– Mary
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Looks like you intended to check the value ofSelectedIndex, not theSelectedItem?
– Ahmed Abdelhameed
Nov 20 '18 at 20:51
|
show 1 more comment
2
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
Do you mean.SelectedIndex? The.Textproperty of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.
– Mary
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Looks like you intended to check the value ofSelectedIndex, not theSelectedItem?
– Ahmed Abdelhameed
Nov 20 '18 at 20:51
2
2
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
Do you mean
.SelectedIndex? The .Text property of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.– Mary
Nov 20 '18 at 20:51
Do you mean
.SelectedIndex? The .Text property of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.– Mary
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Looks like you intended to check the value of
SelectedIndex, not the SelectedItem?– Ahmed Abdelhameed
Nov 20 '18 at 20:51
Looks like you intended to check the value of
SelectedIndex, not the SelectedItem?– Ahmed Abdelhameed
Nov 20 '18 at 20:51
|
show 1 more comment
2 Answers
2
active
oldest
votes
0
Thank you all for your help! I solved the problem, by adding CDbl() just before the user input, used Option Strict On, and used SelectedIndex() instead of SelectedItem().
Here is the code:
If ComboBox1.SelectedIndex = 0 Then
Label4.Text = "Your weight on Mercury" & " is " & (CDbl(TextBox1.Text) * 0.378)
ElseIf ComboBox1.SelectedIndex = 1 Then
Label4.Text = "Your weight on Venus" & " is " & (CDbl(TextBox1.Text) * 0.905)
ElseIf ComboBox1.SelectedIndex = 2 Then
Label4.Text = "Your weight on Earth" & " is " & (CDbl(TextBox1.Text) * 1.0)
ElseIf ComboBox1.SelectedIndex = 3 Then
Label4.Text = "Your weight on Mars" & " is " & (CDbl(TextBox1.Text) * 0.379)
ElseIf ComboBox1.SelectedIndex = 4 Then
Label4.Text = "Your weight on Jupiter" & " is " & (CDbl(TextBox1.Text) * 2.529)
ElseIf ComboBox1.SelectedIndex = 5 Then
Label4.Text = "Your weight on Saturn" & " is " & (CDbl(TextBox1.Text) * 1.066)
ElseIf ComboBox1.SelectedIndex = 6 Then
Label4.Text = "Your weight on Uranus" & " is " & (CDbl(TextBox1.Text) * 0.903)
ElseIf ComboBox1.SelectedIndex = 7 Then
Label4.Text = "Your weight on Neptune" & " is " & (CDbl(TextBox1.Text) * 1.096)
ElseIf ComboBox1.SelectedIndex = 8 Then
Label4.Text = "Your weight on Pluto" & " is " & (CDbl(TextBox1.Text) * 0.069)
End If
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
1
UsingCDblwill fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by usingTryParse(Double.TryParsein your case) as suggested by LarsTech in the comments above.
– Ahmed Abdelhameed
Nov 20 '18 at 22:03
add a comment |
0
Use data-binding instead of If else
and Double.TryParse instead of CDbl for conversions from string to integers
and & instead of + when combining strings(or String interpolation).
Option Strict On - always (which you already did)
Public Class Planet
Public ReadOnly Property Name As String
Public ReadOnly Property WeightFactor As Double
Public Sub New(name As String, weightFactor As Double)
Me.Name = name
Me.WeightFactor = weightFactor
End Sub
End Class
' Create planets and bind it to the ComboBox
' Form constructor
Public Sub New()
InitializeComponent()
Dim planets As New List(Of Planet) From
{
New Planet("Mercury", 0.378),
New Planet("Venus", 0.905),
New Planet("Earth", 1.0),
New Planet("Mars", 0.379),
}
' Bind planets to combobox
ComboBox1.DisplayMember = "Name" ' Name of the property used for displaying text
ComboBox1.ValueMember = "WeightFactor" ' Name of the property used as selected value
ComboBox1.DataSource = planets
End Sub
Then your calculation code will look simpler
Dim personWeight AS Double
If Double.TryParse(textbox1.Text, personWeight) Then
' SelectedItem is instance of selected planet
Dim planet = DirectCast(ComboBox1.SelectedItem, Planet)
Dim weightOnPlanet = personWeight * planet.WeightFactor
Label4.Text = $"Your weight on {planet.Name} is {weightOnPlanet}"
End If
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
draft saved
draft discarded
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53401161%2fvb-net-input-string-was-not-in-a-correct-format-using-convert-todouble%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
0
Thank you all for your help! I solved the problem, by adding CDbl() just before the user input, used Option Strict On, and used SelectedIndex() instead of SelectedItem().
Here is the code:
If ComboBox1.SelectedIndex = 0 Then
Label4.Text = "Your weight on Mercury" & " is " & (CDbl(TextBox1.Text) * 0.378)
ElseIf ComboBox1.SelectedIndex = 1 Then
Label4.Text = "Your weight on Venus" & " is " & (CDbl(TextBox1.Text) * 0.905)
ElseIf ComboBox1.SelectedIndex = 2 Then
Label4.Text = "Your weight on Earth" & " is " & (CDbl(TextBox1.Text) * 1.0)
ElseIf ComboBox1.SelectedIndex = 3 Then
Label4.Text = "Your weight on Mars" & " is " & (CDbl(TextBox1.Text) * 0.379)
ElseIf ComboBox1.SelectedIndex = 4 Then
Label4.Text = "Your weight on Jupiter" & " is " & (CDbl(TextBox1.Text) * 2.529)
ElseIf ComboBox1.SelectedIndex = 5 Then
Label4.Text = "Your weight on Saturn" & " is " & (CDbl(TextBox1.Text) * 1.066)
ElseIf ComboBox1.SelectedIndex = 6 Then
Label4.Text = "Your weight on Uranus" & " is " & (CDbl(TextBox1.Text) * 0.903)
ElseIf ComboBox1.SelectedIndex = 7 Then
Label4.Text = "Your weight on Neptune" & " is " & (CDbl(TextBox1.Text) * 1.096)
ElseIf ComboBox1.SelectedIndex = 8 Then
Label4.Text = "Your weight on Pluto" & " is " & (CDbl(TextBox1.Text) * 0.069)
End If
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
1
UsingCDblwill fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by usingTryParse(Double.TryParsein your case) as suggested by LarsTech in the comments above.
– Ahmed Abdelhameed
Nov 20 '18 at 22:03
add a comment |
0
Thank you all for your help! I solved the problem, by adding CDbl() just before the user input, used Option Strict On, and used SelectedIndex() instead of SelectedItem().
Here is the code:
If ComboBox1.SelectedIndex = 0 Then
Label4.Text = "Your weight on Mercury" & " is " & (CDbl(TextBox1.Text) * 0.378)
ElseIf ComboBox1.SelectedIndex = 1 Then
Label4.Text = "Your weight on Venus" & " is " & (CDbl(TextBox1.Text) * 0.905)
ElseIf ComboBox1.SelectedIndex = 2 Then
Label4.Text = "Your weight on Earth" & " is " & (CDbl(TextBox1.Text) * 1.0)
ElseIf ComboBox1.SelectedIndex = 3 Then
Label4.Text = "Your weight on Mars" & " is " & (CDbl(TextBox1.Text) * 0.379)
ElseIf ComboBox1.SelectedIndex = 4 Then
Label4.Text = "Your weight on Jupiter" & " is " & (CDbl(TextBox1.Text) * 2.529)
ElseIf ComboBox1.SelectedIndex = 5 Then
Label4.Text = "Your weight on Saturn" & " is " & (CDbl(TextBox1.Text) * 1.066)
ElseIf ComboBox1.SelectedIndex = 6 Then
Label4.Text = "Your weight on Uranus" & " is " & (CDbl(TextBox1.Text) * 0.903)
ElseIf ComboBox1.SelectedIndex = 7 Then
Label4.Text = "Your weight on Neptune" & " is " & (CDbl(TextBox1.Text) * 1.096)
ElseIf ComboBox1.SelectedIndex = 8 Then
Label4.Text = "Your weight on Pluto" & " is " & (CDbl(TextBox1.Text) * 0.069)
End If
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
1
UsingCDblwill fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by usingTryParse(Double.TryParsein your case) as suggested by LarsTech in the comments above.
– Ahmed Abdelhameed
Nov 20 '18 at 22:03
add a comment |
0
0
0
Thank you all for your help! I solved the problem, by adding CDbl() just before the user input, used Option Strict On, and used SelectedIndex() instead of SelectedItem().
Here is the code:
If ComboBox1.SelectedIndex = 0 Then
Label4.Text = "Your weight on Mercury" & " is " & (CDbl(TextBox1.Text) * 0.378)
ElseIf ComboBox1.SelectedIndex = 1 Then
Label4.Text = "Your weight on Venus" & " is " & (CDbl(TextBox1.Text) * 0.905)
ElseIf ComboBox1.SelectedIndex = 2 Then
Label4.Text = "Your weight on Earth" & " is " & (CDbl(TextBox1.Text) * 1.0)
ElseIf ComboBox1.SelectedIndex = 3 Then
Label4.Text = "Your weight on Mars" & " is " & (CDbl(TextBox1.Text) * 0.379)
ElseIf ComboBox1.SelectedIndex = 4 Then
Label4.Text = "Your weight on Jupiter" & " is " & (CDbl(TextBox1.Text) * 2.529)
ElseIf ComboBox1.SelectedIndex = 5 Then
Label4.Text = "Your weight on Saturn" & " is " & (CDbl(TextBox1.Text) * 1.066)
ElseIf ComboBox1.SelectedIndex = 6 Then
Label4.Text = "Your weight on Uranus" & " is " & (CDbl(TextBox1.Text) * 0.903)
ElseIf ComboBox1.SelectedIndex = 7 Then
Label4.Text = "Your weight on Neptune" & " is " & (CDbl(TextBox1.Text) * 1.096)
ElseIf ComboBox1.SelectedIndex = 8 Then
Label4.Text = "Your weight on Pluto" & " is " & (CDbl(TextBox1.Text) * 0.069)
End If
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
Thank you all for your help! I solved the problem, by adding CDbl() just before the user input, used Option Strict On, and used SelectedIndex() instead of SelectedItem().
Here is the code:
If ComboBox1.SelectedIndex = 0 Then
Label4.Text = "Your weight on Mercury" & " is " & (CDbl(TextBox1.Text) * 0.378)
ElseIf ComboBox1.SelectedIndex = 1 Then
Label4.Text = "Your weight on Venus" & " is " & (CDbl(TextBox1.Text) * 0.905)
ElseIf ComboBox1.SelectedIndex = 2 Then
Label4.Text = "Your weight on Earth" & " is " & (CDbl(TextBox1.Text) * 1.0)
ElseIf ComboBox1.SelectedIndex = 3 Then
Label4.Text = "Your weight on Mars" & " is " & (CDbl(TextBox1.Text) * 0.379)
ElseIf ComboBox1.SelectedIndex = 4 Then
Label4.Text = "Your weight on Jupiter" & " is " & (CDbl(TextBox1.Text) * 2.529)
ElseIf ComboBox1.SelectedIndex = 5 Then
Label4.Text = "Your weight on Saturn" & " is " & (CDbl(TextBox1.Text) * 1.066)
ElseIf ComboBox1.SelectedIndex = 6 Then
Label4.Text = "Your weight on Uranus" & " is " & (CDbl(TextBox1.Text) * 0.903)
ElseIf ComboBox1.SelectedIndex = 7 Then
Label4.Text = "Your weight on Neptune" & " is " & (CDbl(TextBox1.Text) * 1.096)
ElseIf ComboBox1.SelectedIndex = 8 Then
Label4.Text = "Your weight on Pluto" & " is " & (CDbl(TextBox1.Text) * 0.069)
End If
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
answered Nov 20 '18 at 21:13
surrealismsurrealism
1
1
1
UsingCDblwill fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by usingTryParse(Double.TryParsein your case) as suggested by LarsTech in the comments above.
– Ahmed Abdelhameed
Nov 20 '18 at 22:03
add a comment |
1
UsingCDblwill fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by usingTryParse(Double.TryParsein your case) as suggested by LarsTech in the comments above.
– Ahmed Abdelhameed
Nov 20 '18 at 22:03
1
1
Using
CDbl will fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by using TryParse (Double.TryParse in your case) as suggested by LarsTech in the comments above.– Ahmed Abdelhameed
Nov 20 '18 at 22:03
Using
CDbl will fail if the user input is not a number. You need to validate the user input to make sure it's a number that can be casted to Double. The standard way of doing so is by using TryParse (Double.TryParse in your case) as suggested by LarsTech in the comments above.– Ahmed Abdelhameed
Nov 20 '18 at 22:03
add a comment |
0
Use data-binding instead of If else
and Double.TryParse instead of CDbl for conversions from string to integers
and & instead of + when combining strings(or String interpolation).
Option Strict On - always (which you already did)
Public Class Planet
Public ReadOnly Property Name As String
Public ReadOnly Property WeightFactor As Double
Public Sub New(name As String, weightFactor As Double)
Me.Name = name
Me.WeightFactor = weightFactor
End Sub
End Class
' Create planets and bind it to the ComboBox
' Form constructor
Public Sub New()
InitializeComponent()
Dim planets As New List(Of Planet) From
{
New Planet("Mercury", 0.378),
New Planet("Venus", 0.905),
New Planet("Earth", 1.0),
New Planet("Mars", 0.379),
}
' Bind planets to combobox
ComboBox1.DisplayMember = "Name" ' Name of the property used for displaying text
ComboBox1.ValueMember = "WeightFactor" ' Name of the property used as selected value
ComboBox1.DataSource = planets
End Sub
Then your calculation code will look simpler
Dim personWeight AS Double
If Double.TryParse(textbox1.Text, personWeight) Then
' SelectedItem is instance of selected planet
Dim planet = DirectCast(ComboBox1.SelectedItem, Planet)
Dim weightOnPlanet = personWeight * planet.WeightFactor
Label4.Text = $"Your weight on {planet.Name} is {weightOnPlanet}"
End If
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
add a comment |
0
Use data-binding instead of If else
and Double.TryParse instead of CDbl for conversions from string to integers
and & instead of + when combining strings(or String interpolation).
Option Strict On - always (which you already did)
Public Class Planet
Public ReadOnly Property Name As String
Public ReadOnly Property WeightFactor As Double
Public Sub New(name As String, weightFactor As Double)
Me.Name = name
Me.WeightFactor = weightFactor
End Sub
End Class
' Create planets and bind it to the ComboBox
' Form constructor
Public Sub New()
InitializeComponent()
Dim planets As New List(Of Planet) From
{
New Planet("Mercury", 0.378),
New Planet("Venus", 0.905),
New Planet("Earth", 1.0),
New Planet("Mars", 0.379),
}
' Bind planets to combobox
ComboBox1.DisplayMember = "Name" ' Name of the property used for displaying text
ComboBox1.ValueMember = "WeightFactor" ' Name of the property used as selected value
ComboBox1.DataSource = planets
End Sub
Then your calculation code will look simpler
Dim personWeight AS Double
If Double.TryParse(textbox1.Text, personWeight) Then
' SelectedItem is instance of selected planet
Dim planet = DirectCast(ComboBox1.SelectedItem, Planet)
Dim weightOnPlanet = personWeight * planet.WeightFactor
Label4.Text = $"Your weight on {planet.Name} is {weightOnPlanet}"
End If
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
add a comment |
0
0
0
Use data-binding instead of If else
and Double.TryParse instead of CDbl for conversions from string to integers
and & instead of + when combining strings(or String interpolation).
Option Strict On - always (which you already did)
Public Class Planet
Public ReadOnly Property Name As String
Public ReadOnly Property WeightFactor As Double
Public Sub New(name As String, weightFactor As Double)
Me.Name = name
Me.WeightFactor = weightFactor
End Sub
End Class
' Create planets and bind it to the ComboBox
' Form constructor
Public Sub New()
InitializeComponent()
Dim planets As New List(Of Planet) From
{
New Planet("Mercury", 0.378),
New Planet("Venus", 0.905),
New Planet("Earth", 1.0),
New Planet("Mars", 0.379),
}
' Bind planets to combobox
ComboBox1.DisplayMember = "Name" ' Name of the property used for displaying text
ComboBox1.ValueMember = "WeightFactor" ' Name of the property used as selected value
ComboBox1.DataSource = planets
End Sub
Then your calculation code will look simpler
Dim personWeight AS Double
If Double.TryParse(textbox1.Text, personWeight) Then
' SelectedItem is instance of selected planet
Dim planet = DirectCast(ComboBox1.SelectedItem, Planet)
Dim weightOnPlanet = personWeight * planet.WeightFactor
Label4.Text = $"Your weight on {planet.Name} is {weightOnPlanet}"
End If
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
Use data-binding instead of If else
and Double.TryParse instead of CDbl for conversions from string to integers
and & instead of + when combining strings(or String interpolation).
Option Strict On - always (which you already did)
Public Class Planet
Public ReadOnly Property Name As String
Public ReadOnly Property WeightFactor As Double
Public Sub New(name As String, weightFactor As Double)
Me.Name = name
Me.WeightFactor = weightFactor
End Sub
End Class
' Create planets and bind it to the ComboBox
' Form constructor
Public Sub New()
InitializeComponent()
Dim planets As New List(Of Planet) From
{
New Planet("Mercury", 0.378),
New Planet("Venus", 0.905),
New Planet("Earth", 1.0),
New Planet("Mars", 0.379),
}
' Bind planets to combobox
ComboBox1.DisplayMember = "Name" ' Name of the property used for displaying text
ComboBox1.ValueMember = "WeightFactor" ' Name of the property used as selected value
ComboBox1.DataSource = planets
End Sub
Then your calculation code will look simpler
Dim personWeight AS Double
If Double.TryParse(textbox1.Text, personWeight) Then
' SelectedItem is instance of selected planet
Dim planet = DirectCast(ComboBox1.SelectedItem, Planet)
Dim weightOnPlanet = personWeight * planet.WeightFactor
Label4.Text = $"Your weight on {planet.Name} is {weightOnPlanet}"
End If
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
answered Nov 21 '18 at 2:14
FabioFabio
19.5k22044
19.5k22044
add a comment |
add a comment |
draft saved
draft discarded
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
draft saved
draft discarded
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53401161%2fvb-net-input-string-was-not-in-a-correct-format-using-convert-todouble%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
2
Always use TryParse instead. You are assuming SelectedItem is a number. Enable "Option Strict On" at the top of your file.
– LarsTech
Nov 20 '18 at 20:44
It seems, from your code, that Combobox1.SelectedItem() is probably holding the name of a planet, so converting "Mars" to a double clearly wouldn't work. Perhaps you should be converting TextBox1.Text to double, which looks like it is supposed to be holding a number?
– soohoonigan
Nov 20 '18 at 20:49
Do you mean
.SelectedIndex? The.Textproperty of a TextBox is a string. Don't try to multiply strings by numbers even if it appears to work sometimes. Turning on Option Strict will save you odd runtime errors. A user is not guaranteed to enter what you expect.– Mary
Nov 20 '18 at 20:51
Also, in your "If" statements, I think the Combobox1.SelectedIndex is the property you are after, which will hold an integer. SelectedItem, when cast to a string, will have the planet's name
– soohoonigan
Nov 20 '18 at 20:51
Looks like you intended to check the value of
SelectedIndex, not theSelectedItem?– Ahmed Abdelhameed
Nov 20 '18 at 20:51