"Index and length must refer to a location within the string. Parameter name: length"

[stuart1512]

i am creatign a program to get a duration from the user and the amound per second. it calculates the price per second for a phone call but i have an issue with 2 lines

varSeconds = CType(tbCallLength.Text.Substring(Sep2, 2), Double)
and
varPence = CType(tbCallPrice.Text.Substring(Sep4, 2), Double)

with this error message "Index and length must refer to a location within the string. Parameter name: length"

can u help please, here is the whole of my code

Option Strict On
Public Class frmCallCalculator

    Dim Sep1, Sep2, Sep3, Sep4 As Integer
    Dim varMinutes, varSeconds As Double
    Dim varCal1, varCal2 As Double
    Dim varPounds, varPence As Double

    Private Sub btnCalculatePrice_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculatePrice.Click

        Call Minutes()
        Call Seconds()
        Call Pounds()
        Call Pence()

        varCal1 = CType(varSeconds + (varMinutes * 60), Double)
        varCal2 = varPence + (varPounds * 100)

        tbAnswer.Text = CType(varCal1 * varCal2, String)
    End Sub

    Private Sub Minutes()
        Sep1 = InStr(1, tbCallLength.Text, ":")
        Sep1 = Sep1 - 1
        varMinutes = CType(tbCallLength.Text.Substring(0, Sep1), Double)
    End Sub

    Private Sub Seconds()
        Sep2 = InStr(1, tbCallLength.Text, ":")
        Sep2 = Sep2 + 1
        varSeconds = CType(tbCallLength.Text.Substring(Sep2, 2), Double)
    End Sub

    Private Sub Pounds()
        Sep3 = InStr(2, tbCallPrice.Text, ".")
        Sep3 = Sep3 - 1
        varPounds = CType(tbCallPrice.Text.Substring(2, Sep3), Double)
    End Sub

    Private Sub Pence()
        Sep4 = InStr(2, tbCallPrice.Text, ".")
        Sep4 = Sep4 + 1
        varPence = CType(tbCallPrice.Text.Substring(Sep4, 2), Double)
    End Sub
End Class

[Megalith]

hey stuart,any reason you are using a string to represent the time duration? vb.net has in built functions to deal with times, problem with what you are doing is you need to parse the string, what if the user input a time as "Hello world"?

you could for instance use TimeSpan (http://msdn.microsoft.com/en-us/library/system.timespan_properties%28VS.80%29.aspx) then enter a time in one of several formats

Dim days as Integer = 0
Dim hours As Integer = 0
Dim minutes As Integer = 400
Dim seconds As Integer = 30
Dim Duration as New TimeSpan(days, hours, minutes, seconds)
Console.WriteLine(Duration.TotalSeconds)

This will output to the console the number of seconds in 400m30s, you can then multiply this by the cost per second and divide by 100 to give the value in pounds and pence.

[stuart1512]

its one of the tasks that i have to get the user to input then time and price themselves using the method that i am using now but i just dont get the reason for the error to appear

[Megalith]

ok gimme a mo will try the code

[stuart1512]

ive only got three text boxes and a button

[Megalith]

ok found a few things. first in your minutes you find the ':' and subtract 1 (should be 3) then you dont use the variable in the correct context (you use it for the length which happens to also be 2) in the seconds routine you find the ':' which is 3 and then you add one, then you look for 2 characters. let me put this better.

the 2 string functions you use have different index bases. instr is 1 based and Substring is zero based. say you have this as the string
12:34
instr provides the result 3 for the ':'
12:34
12345
so to get the first 2 digits you need substring(0,2) and for the last 2 you need (3,2)

12:34
01234

hope this helps, you will need to adjust all your subs. just to help further the seconds and pence subs do not need the line that adds 1