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Validation to ensure value entered is a integer

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1

I want a validation method that ensures that value entered is valid, it must be a integer (can include negative) and must not be blank. I have written this code, however not correct, can someone help me please. Thank you

If (b <> Integer Or " ") Then
 Console.WriteLine("Value entered must be a number")
 End If


new code:
Line98:
 Console.WriteLine("Please input the value of, B:")
 b = Console.ReadLine()
 If Not Integer.TryParse(b, New Integer) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

so i used a select statement, and if a user enters "abckak" any non numerical data i get an error Unhandled Exception: System.InvalidCastException: Conversion from string "gakjdg" to type 'Integer' is not valid.

how could this be fixed, this is a quick example of my code

 Console.WriteLine("..........Main Menu..........")
 Console.WriteLine("Please input 1 ")
 Console.WriteLine("Please input 2")
 Console.WriteLine("Please input 3 ")
 Console.WriteLine("Please input 4 ")
 Console.WriteLine("Please input 5 for Help")
 Console.WriteLine("Please input 6 to Exit")

 Console.WriteLine("Please enter your choice: ")

 Choice = Console.ReadLine()
 Select Case Choice

case1; etc

Case Else
 Console.WriteLine("Error: " & Choice & " is not a option, Please try again")

vb.net validation

share|improve this question

edited Mar 27 at 21:46

loco3424

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If Not Integer.TryParse(b, New Integer) Then.... This is a quick solution and would suit what you are looking for. Please see more there about the TryParse...
  
  – Çöđěxěŕ
  Mar 27 at 20:40
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Çöđěxěŕ, i tried that however, and i input f lets just say, i get error Unhandled Exception: System.InvalidCastException: Conversion from string "f" to type 'Integer' is not valid
  
  – loco3424
  Mar 27 at 20:56
  
  

  
  
  
  

add a comment | 

1

I want a validation method that ensures that value entered is valid, it must be a integer (can include negative) and must not be blank. I have written this code, however not correct, can someone help me please. Thank you

If (b <> Integer Or " ") Then
 Console.WriteLine("Value entered must be a number")
 End If


new code:
Line98:
 Console.WriteLine("Please input the value of, B:")
 b = Console.ReadLine()
 If Not Integer.TryParse(b, New Integer) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

so i used a select statement, and if a user enters "abckak" any non numerical data i get an error Unhandled Exception: System.InvalidCastException: Conversion from string "gakjdg" to type 'Integer' is not valid.

how could this be fixed, this is a quick example of my code

 Console.WriteLine("..........Main Menu..........")
 Console.WriteLine("Please input 1 ")
 Console.WriteLine("Please input 2")
 Console.WriteLine("Please input 3 ")
 Console.WriteLine("Please input 4 ")
 Console.WriteLine("Please input 5 for Help")
 Console.WriteLine("Please input 6 to Exit")

 Console.WriteLine("Please enter your choice: ")

 Choice = Console.ReadLine()
 Select Case Choice

case1; etc

Case Else
 Console.WriteLine("Error: " & Choice & " is not a option, Please try again")

vb.net validation

share|improve this question

edited Mar 27 at 21:46

loco3424

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If Not Integer.TryParse(b, New Integer) Then.... This is a quick solution and would suit what you are looking for. Please see more there about the TryParse...
  
  – Çöđěxěŕ
  Mar 27 at 20:40
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Çöđěxěŕ, i tried that however, and i input f lets just say, i get error Unhandled Exception: System.InvalidCastException: Conversion from string "f" to type 'Integer' is not valid
  
  – loco3424
  Mar 27 at 20:56
  
  

  
  
  
  

add a comment | 

I want a validation method that ensures that value entered is valid, it must be a integer (can include negative) and must not be blank. I have written this code, however not correct, can someone help me please. Thank you

If (b <> Integer Or " ") Then
 Console.WriteLine("Value entered must be a number")
 End If


new code:
Line98:
 Console.WriteLine("Please input the value of, B:")
 b = Console.ReadLine()
 If Not Integer.TryParse(b, New Integer) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

so i used a select statement, and if a user enters "abckak" any non numerical data i get an error Unhandled Exception: System.InvalidCastException: Conversion from string "gakjdg" to type 'Integer' is not valid.

how could this be fixed, this is a quick example of my code

 Console.WriteLine("..........Main Menu..........")
 Console.WriteLine("Please input 1 ")
 Console.WriteLine("Please input 2")
 Console.WriteLine("Please input 3 ")
 Console.WriteLine("Please input 4 ")
 Console.WriteLine("Please input 5 for Help")
 Console.WriteLine("Please input 6 to Exit")

 Console.WriteLine("Please enter your choice: ")

 Choice = Console.ReadLine()
 Select Case Choice

case1; etc

Case Else
 Console.WriteLine("Error: " & Choice & " is not a option, Please try again")

vb.net validation

share|improve this question

edited Mar 27 at 21:46

loco3424

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

If (b <> Integer Or " ") Then
 Console.WriteLine("Value entered must be a number")
 End If


new code:
Line98:
 Console.WriteLine("Please input the value of, B:")
 b = Console.ReadLine()
 If Not Integer.TryParse(b, New Integer) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

 Console.WriteLine("..........Main Menu..........")
 Console.WriteLine("Please input 1 ")
 Console.WriteLine("Please input 2")
 Console.WriteLine("Please input 3 ")
 Console.WriteLine("Please input 4 ")
 Console.WriteLine("Please input 5 for Help")
 Console.WriteLine("Please input 6 to Exit")

 Console.WriteLine("Please enter your choice: ")

 Choice = Console.ReadLine()
 Select Case Choice

case1; etc

Case Else
 Console.WriteLine("Error: " & Choice & " is not a option, Please try again")

share|improve this question

edited Mar 27 at 21:46

loco3424

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

share|improve this question

edited Mar 27 at 21:46

loco3424

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

asked Mar 27 at 20:22

loco3424loco3424

1044 bronze badges

1 Answer
1

active

oldest

votes

0

Look into Integer.TryParse, it will try and parse the string into a integer if it can, if it can't it wont throw an exception...

 Dim b As Integer
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

If it can parse the input from the user, then b would be the value from the parse, otherwise the value of b is still 0...

Edit Per Comment

Dim b As Integer
Do Until b > 0
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) OrElse b <= 0 Then
 Console.WriteLine("Value entered must be a number and not equal 0")
 GoTo Line98
 End If
 Loop

share|improve this answer

edited Mar 27 at 21:20

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer one more question bro, If (a = 0) Then Console.WriteLine("Error, number can not be 0, Please Try Again!") GoTo line93 'This will ask for input A again, and repeat the process until a is not 0 End If If Not Integer.TryParse(Console.ReadLine(), a) Then Console.WriteLine(vbLf & "Error: Value entered must be a number") GoTo line93 End If, how would i combine these two
  
  – loco3424
  Mar 27 at 21:06
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @loco3424 with that statement than a/b can be less than 0. In your post you said numbers could be negative... Also if you have further questions please ask another one seperate from the original. Also if this has helped, please vote and accept if this solved your issue so others know this worked.
  
  – Çöđěxěŕ
  Mar 27 at 21:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes sorry a can not be a negative, however problem with your code if i input a valid number it tells me Value entered must be a number and greater than 0 then continues, please help
  
  – loco3424
  Mar 27 at 21:18
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am confused, it seems you keep changing what you are asking. The current code will make sure a user enters a valid number and also make sure that number is greater than 0, if not it loops again...
  
  – Çöđěxěŕ
  Mar 27 at 21:22
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes however before continuing it tells me Value entered must be a number and greater than 0 then continues despite me entering 9
  
  – loco3424
  Mar 27 at 21:23
  

  
  
  
  

 | 
show 6 more comments

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0

Look into Integer.TryParse, it will try and parse the string into a integer if it can, if it can't it wont throw an exception...

 Dim b As Integer
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

If it can parse the input from the user, then b would be the value from the parse, otherwise the value of b is still 0...

Edit Per Comment

Dim b As Integer
Do Until b > 0
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) OrElse b <= 0 Then
 Console.WriteLine("Value entered must be a number and not equal 0")
 GoTo Line98
 End If
 Loop

share|improve this answer

edited Mar 27 at 21:20

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer one more question bro, If (a = 0) Then Console.WriteLine("Error, number can not be 0, Please Try Again!") GoTo line93 'This will ask for input A again, and repeat the process until a is not 0 End If If Not Integer.TryParse(Console.ReadLine(), a) Then Console.WriteLine(vbLf & "Error: Value entered must be a number") GoTo line93 End If, how would i combine these two
  
  – loco3424
  Mar 27 at 21:06
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @loco3424 with that statement than a/b can be less than 0. In your post you said numbers could be negative... Also if you have further questions please ask another one seperate from the original. Also if this has helped, please vote and accept if this solved your issue so others know this worked.
  
  – Çöđěxěŕ
  Mar 27 at 21:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes sorry a can not be a negative, however problem with your code if i input a valid number it tells me Value entered must be a number and greater than 0 then continues, please help
  
  – loco3424
  Mar 27 at 21:18
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am confused, it seems you keep changing what you are asking. The current code will make sure a user enters a valid number and also make sure that number is greater than 0, if not it loops again...
  
  – Çöđěxěŕ
  Mar 27 at 21:22
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes however before continuing it tells me Value entered must be a number and greater than 0 then continues despite me entering 9
  
  – loco3424
  Mar 27 at 21:23
  

  
  
  
  

 | 
show 6 more comments

0

Look into Integer.TryParse, it will try and parse the string into a integer if it can, if it can't it wont throw an exception...

 Dim b As Integer
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

If it can parse the input from the user, then b would be the value from the parse, otherwise the value of b is still 0...

Edit Per Comment

Dim b As Integer
Do Until b > 0
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) OrElse b <= 0 Then
 Console.WriteLine("Value entered must be a number and not equal 0")
 GoTo Line98
 End If
 Loop

share|improve this answer

edited Mar 27 at 21:20

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer one more question bro, If (a = 0) Then Console.WriteLine("Error, number can not be 0, Please Try Again!") GoTo line93 'This will ask for input A again, and repeat the process until a is not 0 End If If Not Integer.TryParse(Console.ReadLine(), a) Then Console.WriteLine(vbLf & "Error: Value entered must be a number") GoTo line93 End If, how would i combine these two
  
  – loco3424
  Mar 27 at 21:06
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @loco3424 with that statement than a/b can be less than 0. In your post you said numbers could be negative... Also if you have further questions please ask another one seperate from the original. Also if this has helped, please vote and accept if this solved your issue so others know this worked.
  
  – Çöđěxěŕ
  Mar 27 at 21:16
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes sorry a can not be a negative, however problem with your code if i input a valid number it tells me Value entered must be a number and greater than 0 then continues, please help
  
  – loco3424
  Mar 27 at 21:18
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I am confused, it seems you keep changing what you are asking. The current code will make sure a user enters a valid number and also make sure that number is greater than 0, if not it loops again...
  
  – Çöđěxěŕ
  Mar 27 at 21:22
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @codexer, yes however before continuing it tells me Value entered must be a number and greater than 0 then continues despite me entering 9
  
  – loco3424
  Mar 27 at 21:23
  

  
  
  
  

 | 
show 6 more comments

Look into Integer.TryParse, it will try and parse the string into a integer if it can, if it can't it wont throw an exception...

 Dim b As Integer
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

If it can parse the input from the user, then b would be the value from the parse, otherwise the value of b is still 0...

Edit Per Comment

Dim b As Integer
Do Until b > 0
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) OrElse b <= 0 Then
 Console.WriteLine("Value entered must be a number and not equal 0")
 GoTo Line98
 End If
 Loop

share|improve this answer

edited Mar 27 at 21:20

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

 Dim b As Integer
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) Then
 Console.WriteLine("Value entered must be a number")
 GoTo Line98
 End If

Dim b As Integer
Do Until b > 0
 Console.WriteLine("Please input the value of, B:") 
 If Not Integer.TryParse(Console.ReadLine(), b) OrElse b <= 0 Then
 Console.WriteLine("Value entered must be a number and not equal 0")
 GoTo Line98
 End If
 Loop

share|improve this answer

edited Mar 27 at 21:20

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges

answered Mar 27 at 20:58

ÇöđěxěŕÇöđěxěŕ

5,43155 gold badges2121 silver badges4444 bronze badges