basically, I want to reverse the numbers. (in the textbox there will be only 2-digit numbers)
if I have Textbox1.text:
12
2
41
71
70
I want to display in the box (Textbox1.text)
21
2
14
17
70
Function:
Public Shared Function Reverse(num As Integer) As Integer
Dim _reverse As Integer = 0
While num <> 0
_reverse *= 10
_reverse += num Mod 10
num \= 10
End While
Return _reverse
End Function
it should work, it actually works, but I don't know how to arrange it to work in all lines.
For Each lines In TextBox1.Lines
Dim rev = Reverse(lines)
lines.Replace(lines, rev)
Next
This is a perfect example of what happens when people try to write code without knowing what the code is supposed to. What the code is supposed to do is not just the end result but the steps to get there. If you don't know what the steps are then you shouldn't be writing any code because it's unlikely that what you write will do anything useful. Code is simply an implementation of logic so you should be getting the logic down first. It doesn't take any programming experience to work out the logic because we could all do this if it was a manual process and that would be the same logic.
So, what are the steps involved?
Get the lines of the text.
Loop over the lines.
Reverse the current line.
Replace the original line with the result of reversing.
Replace the text with the complete results.
If you actually consider each of those steps, it should be obvious that you cannot use a For Each loop because that will only let you get data out of a list, not put data into it. That would make it obvious that a For loop is the right choice, because will let you get data out and put it in. Now you can write code that actually does something useful.
Dim lines = TextBox1.Lines
For i = 0 To lines.GetUpperBound(0)
Dim line = lines(i)
Dim number = CInt(line)
Dim result = Reverse(number)
lines(i) = result.ToString()
Next
TextBox1.Lines = lines
Simple stuff but, again, if you don't know what the code has to actually do, writing code to do it is a challenge. Always break the problem down into smaller parts first, so you can work on each part individually, and always work out the logic you're trying to implement - and test that logic manually - before trying to write code to implement it.
Related
I got a knew problem which should be the last one from my bonus exercise. At first let's explain the rules, I have a word which is shuffle. I want my user to find this word and he has a determined number of tries.
Now I want to let the user know which char from his input (txtBox.Text) was right and which one aren't. So I tried to create a method which is able to Color a char in green If the char is correctly positionned else in red. I ask my teacher and it seems to be a hard thing to do, I tried to find the solution he gave me with richBox but it's way too hard right now, i'm struggling way to much.
So ! I think of something way simpler, or at least i thought it was simpler, I get the user input in a String and I do a loop around it, every time the correct word and the input char doesn't match I replaced it by a dot.
It doesen't work either if I try to put an index to my :
If word(i) IsNot proposition(j) Then
I'm facing an out of bound and if I try without it, it consider my string as an array of 1 and add to my listbox a single dot.
Here's my code :
Public Sub charRight&Wrong()
Dim proposition() As String = {txtInput.Text} //get the proposition from the user
Dim dot As Char = "."
Dim word() As String = {theWord} //theWord represent the right answer
For i = 0 To theWord.Length - 1
For j = 0 To proposition.Length - 1
If word(i) IsNot proposition(j) Then
proposition(j) = dot
End If
Next
Next
lboAttempts.Items.AddRange(proposition.ToArray)
End Sub
I don't really know where I'm wrong I hope you can point it out. Thanks again.
So i want to perform some code N times. N is textbox's value (e.g: 12).
I have no idea how to accomplish this, but something like this is on my mind:
For Each i as 1 in textbox1.text
'some code
Next
or
dim num1 as integer = 0
While num1 < textbox1.text
'some code
num1 += 1
Next
Those were just some ideas that were on my mind when i though about this question, none of above is tested nor tried to code.
Any ideas?
First and foremost, turn on Option Strict. This will save you time in the long run by converting possible runtime errors into compiler errors. At the top of the code file:
Option Strict On
It can also be set for the entire project:
Project Properties -> Compile Tab -> Option Strict selector: On
You can also make it the default for all new projects via:
Tools -> Options -> Projects and Solutions -> VB Defaults
What it Does
TextBox.Text always contains text (hence the clever names). "12" is just a string and is not the same as 12. So, before you can use it, you need to convert from string to integer. Note: If you want to restrict user input to numbers consider using a NumericUpDown.
There are several ways to convert, but considering that the data comes from a user, we have to allow that they may enter "I like pie" instead of numerals. So, we want to use the safest method which in this case is Integer.TryParse:
' declare int var to hold the result
Dim LoopCount As Integer
If Integer.TryParse(TextBox132.Text, LoopCount) Then
' success! LoopCOunt contains the integer value of the Text control
For n As Integer = 0 To LoopCount - 1
' some code to do something
Next
Else
' failed - scold the user with a MessageBox
End if
The comments in the code explain, but first you declare an integer variable to hold the converted value. Integer.TryParse is a function which will return True/False. If it succeeds, your variable will hold the integer value.
See Converting DataTypes for Option Strict for other convert methods and cases where they are appropriate.
This might work, I haven't tried:
Dim repeat_times as Integer = 0
Do Until repeat_times = 10 'times you want to repeat
repeat_times = repeat_times + 1
Console.WriteLine("Hello World") 'or anything you want
Loop
For n As Int32 = 0 To TextBox1.text - 1 was an answer for my question.
In my code,I have now realised I have to use the New Random function, my code was working before with the Randomize and then the numbers but now it comes up with loads of errors and wont even let me run the program. I think it is only a small error but I just need some help to get the final bit going
Heres the code and thanks for any help :)
I cannot get the code to work with the randomly generated number and I have to use the New Random function I cannot use randomize() Does anybody know how to help here is the code.
Dim timestook As Int32 = 1
Dim usersguess As Integer
Dim value = New Random(0 - 19)
Console.WriteLine("You have to guess this number. It is between 1 and 20. Good Luck !")
usersguess = Console.ReadLine()
'keep looping until they get the right value
While usersguess <> value
'now check how it compares to the random value
If usersguess < value Then
timestook = timestook + 1
Console.WriteLine("You're too low. Go higher ")
ElseIf usersguess > value Then
Console.WriteLine("You're too high. Go Lower.")
timestook = timestook + 1
End If
'If they are wrong the code will run again,after telling the user if they are too high or too low.
usersguess = Console.ReadLine()
End While
' Console.WriteLine("You're correct. Well Done")
If usersguess = value Then
Console.WriteLine("You took,{0}", timestook)
End If
Console.ReadLine()
End Sub
You'll want to do some googling on how to use random numbers. Your problem is that you aren't creating a Random object to handle the random number generation.
Here's how you can fix your code:
Dim randNumGen As New Random() 'Create Random object
Dim value As Integer = randNumGen.Next(0, 20) 'set value equal to a new random number between 0-19
Please note that this code could be further refactored for readability and simplicity (like changing timestook = timestook + 1 to timestook += 1 and selecting better variable names like numberOfGuesses as opposed to timestook, etc.
The expression New Random(0-19) does not do at all what you think it does, name it does NOT return an integer. Instead, it creates an instance of a Random object, which is a type that knows how to create new random values. The 0-19 part of the expression is the seed for the Random object's constructor, and is the same as just passing the value -19.
This looks like it's either homework or personal practice, so I feel like you will be better served in this case with a separate example using the Random type for reference than you would if I fixed the code sample in the question for you:
Dim rnd As New Random()
For i As Integer = 0 To 10
Console.WriteLine(rnd.Next(0, 20))
Next i
It's also worth mentioning here that you typically only want one Random object for your entire program, or at least only one Random object for each logical part of your program. Creating new Random objects resets the seeds, and for best results you want to follow the same seed on subsequent calls to the same instance for a while.
I'm trying to create a function which generates a secret encoded message. It takes in three things: a string, for example, "testingtestingonetwothree", as well as the desired number of characters, for example 5, and the desired number of words, for example 5. It generates the message by starting at the first character, and extracting every fifth character through the string, putting these characters into a codeword, then starting at the second character and extracting every fifth character through the string, putting these into a second codeword, and so on. It just outputs a string, with the codewords separated by a space. So for this example it would produce: "tntnt egieh stntr tegwe isooe".
I'm okay at coding but new to VBA. I've made what I think is a valid function, but when it's used in the spreadsheet I get a #VALUE! error: "A value used in the formula is the wrong data type". This is the user defined function I made:
Function encode(strng, numchars, numwords)
Dim word As Integer
Dim step As Integer
Dim temp As String
Dim output As String
For word = 1 To numchars
step = word
temp = ""
Do While step <= Len(strng)
temp = temp & Mid(strng, 1, step)
step = step + numchars
Loop
If word = 1 Then output = temp Else output = output & " " & temp
Next word
encode = output
End Function
And when it's used in the spreadsheet I just call it, as in
=encode(A16,A7,A10)
Where A16 contains testingtestingonetwothree, A7 contains 5 and A10 contains 5.
Does my function seem okay? And is there anything you guys can see which could be giving the value error? Any help would be greatly appreciated, thanks a lot for reading.
EDIT: This now outputs a value, but the wrong value. It outputs: "ttestintestingtesttestingtestingontestingtestingonetwot tetestingtestingtestitestingtestingonetestingtestingonetwoth ", when it should output: "tntnt egieh stntr tegwe isooe". Is there anything you guys can see that my function is doing wrong?
EDIT2: After fixing the Mid function, to
temp = temp & Mid(strng, step, 1)
as per vacip's answer, the function now produces the correct answer.
Ok, everyone says it works, but for me, it doesn't produce the desired output. What the...???
Anyway, I think your Mid function is in the wrong order, try it like this:
temp = temp & Mid(strng, step, 1)
Also, make sure to properly declare your variables, like this:
Function encode(strng As String, numchars As Integer, numwords As Integer) As String
I have also rewritten your IF statement, that one-line thing is strange for me...
If word = 1 Then
output = temp
Else
output = output & " " & temp
End If
This way it worked for me.
Other people have addressed the type problem. Here is a different suggestion. The cipher that you are describing is a simple transposition cipher, specifically a columnar transposition ( https://en.wikipedia.org/wiki/Transposition_cipher#Columnar_transposition )
The way people did this pre-computer was to write the characters into a grid row by row then read them off column by column. In fact -- this is probably still the easiest way to implement it even with computers. Declare a variant which can be redimensioned to be an array with e.g. 5 columns (where 5 is the skip between letters) and the number of rows is chosen to be large enough so that the grid can hold the string. After you load up the characters row by row, read them off column by column using nested for loops.
Once you get a basic example working, you can try to implement a version which uses a key to determine the order that you read off the columns for added security.
Coding classical cryptography/cryptanalysis as an excellent way to learn a programming language. Almost the first thing I do when I try to learn a new language is to implement a Vigenere cipher in it. Even though it is long out of print and can be somewhat tricky to translate to modern dialects of Basic the book "Cryptanalysis for Microcomputers" by Caxton Foster is great fun and can be purchased for just a few dollars from online used bookstores.
You need to define your Function's type. So in this case I believe you would want
Function encode(strng, numchars, numwords) As String
I tested your code exactly as it is, and it worked fine.
So, your problem may be:
A certain argument of your function is not the right type. (I bet the len method is the problem in there).
Check if A16 is really a string. If not, consider converting it to a string before if you want to pass numbers too:
Function encode(strng as variant, numchars as integer, numwords as integer) as string
strng = str(strng)
Check also if A7 and A10 are really integers.
I have a VB.NET application that I use to load various files into a RichTextBox and then scan through the document to find specific words. It's similar to the Find function in Word. The app was running fine until a 5,150 line .sql document run through it and it's taking upwards of 10 minutes to run to completion.
Can anyone recommend a better way of coding it than I have below?
If sqlText.Contains("GRANT") Then
Dim searchstring As String = "GRANT"
Dim count As New List(Of Integer)()
For i As Integer = 0 To rtbFile.Text.Length - 1
If rtbFile.Text.IndexOf(searchstring, i) <> -1 Then
count.Add(rtbFile.Text.IndexOf(searchstring, i))
End If
Next
Try
For i As Integer = 0 To count.Count - 1
rtbFile.Select(count(i), searchstring.Length)
rtbFile.SelectionBackColor = Color.Yellow
rtbFile.SelectionFont = New Font(rtbFile.Font, FontStyle.Bold)
count.RemoveAt(i)
Next
Catch ex As Exception
End Try
rtbFile.Select(rtbFile.Text.Length, 0)
rtbFile.SelectionBackColor = Color.White
rtbFile.SelectionFont = New Font(rtbFile.Font, FontStyle.Regular)
End If
That first loop is killing the performance, you are calling IndexOf for every character in the string. Also the two loops can be merged in to one. Change it to:
rtbFile.SelectionBackColor = Color.Yellow
rtbFile.SelectionFont = New Font(rtbFile.Font, FontStyle.Bold)
For Each m As Match in Regex.Matches(sertbFile.Text, searchstring)
rtbFile.Select(m.Index, searchstring.Length)
Next
This can also be done with a While loop and RichTextBox.Find():
Dim searchstring As String = "GRANT"
Dim index As Integer = rtbFile.Find(searchstring, 0, RichTextBoxFinds.None)
While index <> -1
rtbFile.Select(index, searchstring.Length)
rtbFile.SelectionBackColor = Color.Yellow
rtbFile.SelectionFont = New Font(rtbFile.Font, FontStyle.Bold)
index = rtbFile.Find(searchstring, index + searchstring.Length, RichTextBoxFinds.None)
End While
You've got a few bad things going on here:
First, the following code:
For i As Integer = 0 To rtbFile.Text.Length - 1
If rtbFile.Text.IndexOf(searchstring, i) <> -1 Then
count.Add(rtbFile.Text.IndexOf(searchstring, i))
End If
Next
This is looping through every character in your string, and calling IndexOf on the entire string from that point forward. So your 50,000-character string is running IndexOf 50,000 times, on large strings.
You only need to call IndexOf as many times as you find a string. When your string is found, you increment your start index to that point, and keep searching only from that point.
Next thing, this code:
For i As Integer = 0 To count.Count - 1
...
count.RemoveAt(i)
Next
The RemoveAt line is unnecessary. You're already looping through a list, so you don't need to remove the items as you go along. The way it stands, your loop will skip every other item in your list.
Whoops. I missed a very important point about the IndexOf (and incorrectly assumed it was fed with the end of the last match). See Magnus's answer.
I am not sure where the bottleneck is (and it might very well be from setting the selection itself), but here are my suggestions, roughly in order of priority:
Invoke rtbFile.Text once to avoid any roundtrips to underlying control (perhaps a native Windows control?) and use a variable to store the resulting string. Once the string is obtained in .NET, just keep using it directly unless/until the text may change. If the control is native then a lot of work may be required to simply "get the text".
Use normal item iteration over the count collection (not indexing) and do not remove from the front-of the List when assigning the selections. Removing from the front of a List is "expensive" in that it must shift all items down internally. Also, removing the element is unneeded here and dubious at best: since the collection being modified is also is being iterated which likely leads to incorrect behavior (skipped items), regardless of performance.
Only call IndexOf once per loop and use a variable to avoid a duplicate search. This likely won't have an overall impact, but it does avoid some "extra" work. IndexOf itself is fine and doesn't need to be replaced.
YMMV.