[英]How can I add an error message to my program if the user doesn't enter an integer?
[英]How do I program an Error message if the user presses enter without putting a number in. (e.g. putting a letter or nothing at all)
'the variables
Dim watertemp As Decimal 'changed variable to decimal so that decimal numbers can be input.
Dim fahren As Decimal
Dim newtemp As String
'this code asks the intial question (the temp of the water)
Console.WriteLine("Enter the tempurature of the water, between -273.15 and 100 degrees celcius.")
watertemp = Console.ReadLine
'this code is to work out what the water should be called and the colour of the text it will be displayed in.
If watertemp <= 0 Then
Console.ForegroundColor = ConsoleColor.Blue
Console.WriteLine("The water is freezing")
End If
If watertemp >= 1 And watertemp <= 25 Then
Console.ForegroundColor = ConsoleColor.Cyan
Console.WriteLine("The water is warm")
End If
If watertemp >= 26 And watertemp <= 60 Then
Console.WriteLine("The water is hot")
End If
If watertemp >= 61 And watertemp <= 99 Then
Console.ForegroundColor = ConsoleColor.Magenta
Console.WriteLine("The water is very hot")
End If
If watertemp >= 100 Then
Console.ForegroundColor = ConsoleColor.Red
Console.WriteLine("The water is boiling")
End If
'this code converts the tempurature to fahrenheit
fahren = (9 / 5 * watertemp) + 32
Console.WriteLine("The water is " & (Format(fahren, "0.00")) & " °F")
'this code changes the text back to white
Console.ForegroundColor = ConsoleColor.White
'this code asks the user if they would like to convert another input
Console.WriteLine("Would you like to convert another tempurature?")
newtemp = Console.ReadLine
'this code determines whether to carry on with converting another input or end the program
If newtemp = "no" Then
Console.WriteLine("This is the end of the program")
End If
If newtemp = "yes" Then
Console.WriteLine("What is the tempurature of the water?")
watertemp = Console.ReadLine
End If
fahren = (9 / 5 * watertemp) + 32
Console.WriteLine("The water is " & (Format(fahren, "0.00")) & " °F")
Console.ReadLine()
如果用户输入了程序无法运行的内容,例如字母或什么都没有,我需要有一条错误消息。
我尝试了一些东西,但我不知道我是否做对了,因为我对编码很陌生。
Dim watertemp As Decimal 'changed variable to decimal so that decimal numbers can be input.
Dim fahren As Decimal
Dim newtemp As String
reenter:
'this code asks the intial question (the temp of the water)
Console.WriteLine("Enter the tempurature of the water, between -273.15 and 100 degrees celcius.")
watertemp = Console.ReadLine
If String.IsNullOrEmpty(watertemp) OrElse Not IsNumeric(watertemp) Then
MsgBox("Wrong input.")
GoTo reenter
End If
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