I want to split a String whereever the ' character is present unless there is a question mark in front of it(?') - in that case I don't want to split.
What's the best way to go about doing that?
I'm splitting like so (if the delimiter is a Char):
message.Split(New Char() {"'"C})
And if it's a String:
message.Split(New String() {"break"}, StringSplitOptions.None)
Do I then have to test each item in the given array to see if it ends with a ? char, and then concatenate the Strings again - that just doesn't seem like an optimal solution..?
Do you have to make a regular expression, and how would you do that in vb.net?
You will need a Regex.Split with a (?<!\?)' regex:
Regex.Split(message, "(?<!\?)'")
See the regex demo
The (?<!\?) negative lookbehind will fail the match if a literal ? appears right to the left of the single apostrophe.
In VB.NET, you can use Linq to remove any empty strings you get with this regex split:
Dim message As String = "'sss?'ss'"
Dim my_result() As String = Regex.Split(message, "(?<!\?)'") _
.Where(Function(strn As String) String.IsNullOrWhiteSpace(strn) = False) _
.ToArray()
Console.WriteLine(String.Join(", ", my_result))
' => sss?'ss
Related
I have several strings, e.g.
(3)_(9)--(11).(FT-2)
(10)--(20).(10)/test--(99)
I am trying Regex.Match(here I do no know) to get a list like this:
First sample:
3
_
9
--
11
.
FT-1
Second Sample:
10
--
20
.
10
/test--
99
So there are several numbers in brackets and any text between them.
Can anyone help me doing this in vb.net? A given string returns this list?
One option is to use the Split method of [String]
"(3)_(9)--(11).(FT-2)".Split('()')
Another option is to match everything excluding ( and )
As regex, this would do [^()]+
Breakdown
"[^()]" ' Match any single character NOT present in the list “()”
"+" ' Between one and unlimited times, as many times as possible, giving back as needed (greedy)
You can use following block of code to extract all matches
Try
Dim RegexObj As New Regex("[^()]+", RegexOptions.IgnoreCase)
Dim MatchResults As Match = RegexObj.Match(SubjectString)
While MatchResults.Success
' matched text: MatchResults.Value
' match start: MatchResults.Index
' match length: MatchResults.Length
MatchResults = MatchResults.NextMatch()
End While
Catch ex As ArgumentException
'Syntax error in the regular expression
End Try
This should work:
Dim input As String = "(3)_(9)--(11).(FT-2)"
Dim searchPattern As String = "\((?<keep>[^)]+)\)|(?<=\))(?<keep>[^()]+)"
Dim replacementPattern As String = "${keep}" + Environment.NewLine
Dim output As String = RegEx.Replace(input, searchPattern, replacementPattern)
The simplest way is to use Regex.Split (formulated as a little console test):
Dim input = {"(3)_(9)--(11).(FT-2)", "(10)--(20).(10)/test--(99)"}
For Each s As String In input
Dim parts = Regex.Split(s, "\(|\)")
Console.WriteLine($"Input = {s}")
For Each p As String In parts
Console.WriteLine(p)
Next
Next
Console.ReadKey()
So basically we have a one-liner for the regex part.
The regular expression \(|\) means: split at ( or ) where the braces are escaped with \ because of their special meaning within regex.
The slightly shorter regex [()] where the desired characters are enclosed in [] would produce the same result.
What I'm trying to accomplish
I'm trying to create a function to use string interpolation within VBA. The issue I'm having is that I'm not sure how to replace "\n" with a vbNewLine, as long as it does not have the escape character "\" before it?
What I have found and tried
VBScript does not have a negative look behind as far as I can research.
Below has two examples of Patterns that I have already tried:
Private Sub testingInjectFunction()
Dim dict As New Scripting.Dictionary
dict("test") = "Line"
Debug.Print Inject("${test}1\n${test}2 & link: C:\\notes.txt", dict)
End Sub
Public Function Inject(ByVal source As String, dict As Scripting.Dictionary) As String
Inject = source
Dim regEx As Object
Set regEx = CreateObject("VBScript.RegExp")
regEx.Global = True
' PATTERN # 1 REPLACES ALL '\n'
'regEx.Pattern = "\\n"
' PATTERN # 2 REPLACES EXTRA CHARACTER AS LONG AS IT IS NOT '\'
regEx.Pattern = "[^\\]\\n"
' REGEX REPLACE
Inject = regEx.Replace(Inject, vbNewLine)
' REPLACE ALL '${dICT.KEYS(index)}' WITH 'dICT.ITEMS(index)' VALUES
Dim index As Integer
For index = 0 To dict.Count - 1
Inject = Replace(Inject, "${" & dict.Keys(index) & "}", dict.Items(index))
Next index
End Function
Desired result
Line1
Line2 & link: C:\notes.txt
Result for Pattern # 1: (Replaces when not wanted)
Line1
Line2 & link: C:\
otes.txt
Result for Pattern # 2: (Replaces the 1 in 'Line1')
Line
Line2 & link: C:\\notes.txt
Summary question
I can easily write code that doesn't use Regular Expressions that can achieve my desired goal but want to see if there is a way with Regular Expressions in VBA.
How can I use Regular Expressions in VBA to Replace "\n" with a vbNewLine, as long as it does not have the escape character "\" before it?
Yes, you may use a regex here. Since the backslash is not used to escape itself in these strings, you may modify your solution like this:
regEx.Pattern = "(^|[^\\])\\n"
S = regEx.Replace(S, "$1" & vbNewLine)
It will match and capture any char but \ before \n and then will put it back with the $1 placeholder. As there is a chance that \n appears at the start of the string, ^ - the start of string anchor - is added as an alternative into the capturing group.
Pattern details
(^|[^\\]) - Capturing group 1: start of string (^) or (|) any char but a backslash ([^\\])
\\ - a backslash
n - a n char.
I am using VB.NET to write a winforms application, how can I use regular expression to remove spaces between "[" and "]" in a string?
For example, for a string
"[Product Name] Like '%Dragon Ball%' AND [Product Type] Like '%Toy%'"
I want the result to be
"[ProductName] Like '%Dragon Ball%' AND [ProductType] Like '%Toy%'"
I tried this, but it is not working:
Public Function RemoveSpaceInFieldNames(ByVal expression As String) As String
Dim regex As RegularExpressions.Regex = New
RegularExpressions.Regex(String.Format("\{0}\s*\{1}", "[", "]"))
Return regex.Replace(expression, String.Empty)
End Function
See regex in use here
(?<=\[[^]]*)\s
(?<=\[[^]]*) Positive lookbehind ensuring the following matches
\[ Match [ literally
[^]]* Match any character except ] any number of times
\s Match any whitespace character
You can append (?=[^[]*]) if you want to ensure there's a ] sometime afterwards as well, but, based on your sample, I don't think this is necessary.
Alternatively, you can also use \s(?=[^[]*]) with the Right to Left modifier as this link shows.
Replace with an empty string.
Result: [ProductName] Like '%Dragon Ball%' AND [ProductType] Like '%Toy%'
Thank you so much ctwheels! Your answer works perfectly!!!
Public Function RemoveSpaceInFieldNames(ByVal expression As String) As String
Dim regex As RegularExpressions.Regex = New RegularExpressions.Regex("(?<=\[[^]]*)\s")
Return regex.Replace(expression, String.Empty)
End Function
I have a list of original words and replace with words which I want to replace occurrence of the original words in some sentences to the replace words.
For example my list:
theabove the above
myaddress my address
So the sentence "This is theabove." will become "This is the above."
I am using Regular Expression in VB like this:
Dim strPattern As String
Dim regex As New RegExp
regex.Global = True
If Not IsEmpty(myReplacementList) Then
For intRow = 0 To UBound(myReplacementList, 2)
strReplaceWith = IIf(IsNull(myReplacementList(COL_REPLACEMENTWORD, intRow)), " ", varReplacements(COL_REPLACEMENTWORD, intRow))
strPattern = "\b" & myReplacementList(COL_ORIGINALWORD, intRow) & "\b"
regex.Pattern = strPattern
TextToCleanUp = regex.Replace(TextToReplace, strReplaceWith)
Next
End If
I loop all entries in my list myReplacementList against the text TextToReplace I want to process, and the replacement have to be whole word so I used the "\b" token around the original word.
It works well but I have a problem when the original words contain some special characters for example
overla) overlay
I try to escape the ) in the pattern but it does not work:
\boverla\)\\b
I can't replace the sentence "This word is overla) with that word." to "This word is overlay with that word."
Not sure what is missing? Is regular expression the way to the above scenario?
I'd use string.replace().
That way you don't have to escape special chars .. only these: ""!
See here for examples: http://www.dotnetperls.com/replace-vbnet
Regex is good if your looking for patterns. Or renaming your mp3 collection ;-) and much, much more. But in your case, I'd use string.replace().
I am trying to split a long string based on an array of words. For Example:
Words: trying, long, array
Sentence: "I am trying to split a long string based on an array of words."
Resulting string array:
I am
trying
to split a
long
string based on an
array
of words
Multiple instances of the same word is likely, so having two instances of trying cause a split, or of array, will probably happen.
Is there an easy way to do this in .NET?
The easiest way to keep the delimiters in the result is to use the Regex.Split method and construct a pattern using alternation in a group. The group is key to including the delimiters as part of the result, otherwise it will drop them. The pattern would look like (word1|word2|wordN) and the parentheses are for grouping. Also, you should always escape each word, using the Regex.Escape method, to avoid having them incorrectly interpreted as regex metacharacters.
I also recommend reading my answer (and answers of others) to a similar question for further details: How do I split a string by strings and include the delimiters using .NET?
Since I answered that question in C#, here's a VB.NET version:
Dim input As String = "I am trying to split a long string based on an array of words."
Dim words As String() = { "trying", "long", "array" }
If (words.Length > 0)
Dim pattern As String = "(" + String.Join("|", words.Select(Function(s) Regex.Escape(s)).ToArray()) + ")"
Dim result As String() = Regex.Split(input, pattern)
For Each s As String in result
Console.WriteLine(s)
Next
Else
' nothing to split '
Console.WriteLine(input)
End If
If you need to trim the spaces around each word being split you can prefix and suffix \s* to the pattern to match surrounding whitespace:
Dim pattern As String = "\s*(" + String.Join("|", words.Select(Function(s) Regex.Escape(s)).ToArray()) + ")\s*"
If you're using .NET 4.0 you can drop the ToArray() call inside the String.Join method.
EDIT: BTW, you need to decide up front how you want the split to work. Should it match individual words or words that are a substring of other words? For example, if your input had the word "belong" in it, the above solution would split on "long", resulting in {"be", "long"}. Is that desired? If not, then a minor change to the pattern will ensure the split matches complete words. This is accomplished by surrounding the pattern with a word-boundary \b metacharacter:
Dim pattern As String = "\s*\b(" + String.Join("|", words.Select(Function(s) Regex.Escape(s)).ToArray()) + ")\b\s*"
The \s* is optional per my earlier mention about trimming.
You could use a regular expression.
(.*?)((?:trying)|(?:long)|(?:array))(.*)
will give you three groups if it matches:
1) The bit before the first instance of any of the split words.
2) The split word itself.
3) The rest of the string.
You can keep matching on (3) until you run out of matches.
I've played around with this but I can't get a single regex that will split on all instances of the target words. Maybe someone with more regex-fu can explain how.
I've assumed that VB has regex support. If not, I'd recommend using a different language. Certainly C# has regexes.
You can split with " ",
and than go through the words and see which one is contained in the "splitting words" array
Dim testS As String = "I am trying to split a long string based on an array of words."
Dim splitON() As String = New String() {"trying", "long", "array"}
Dim newA() As String = testS.Split(splitON, StringSplitOptions.RemoveEmptyEntries)
Something like this
Dim testS As String = "I am trying to split a long string based on a long array of words."
Dim splitON() As String = New String() {"long", "trying", "array"}
Dim result As New List(Of String)
result.Add(testS)
For Each spltr As String In splitON
Dim NewResult As New List(Of String)
For Each s As String In result
Dim a() As String = Strings.Split(s, spltr)
If a.Length <> 0 Then
For z As Integer = 0 To a.Length - 1
If a(z).Trim <> "" Then NewResult.Add(a(z).Trim)
NewResult.Add(spltr)
Next
NewResult.RemoveAt(NewResult.Count - 1)
End If
Next
result = New List(Of String)
result.AddRange(NewResult)
Next
Peter, I hope the below would be suitable for Split string by array of words using Regex
// Input
String input = "insert into tbl1 inserttbl2 insert into tbl2 update into tbl3
updatededle into tbl4 update into tbl5";
//Regex Exp
String[] arrResult = Regex.Split(input, #"\s+(?=(?:insert|update|delete)\s+)",
RegexOptions.IgnoreCase);
//Output
[0]: "insert into tbl1 inserttbl2"
[1]: "insert into tbl2"
[2]: "update into tbl3 updatededle into tbl4"
[3]: "update into tbl5"