Develop Reference

How do extract data between two terms in a string?

<a href="https://genius.com/Run-the-jewels-lie-cheat-steal-lyrics" class=" song_link" title="Lie, Cheat, Steal by Run the Jewels">
I'm trying to extract the link that's in between href="", and set it to a string. Is there any way to do that?
The data in it will change consistantly, it's not always gonna be the same domain. Thanks in advance.

Quick and easy: find the text between href=" and the next " (as " will never appear in the value):
Int32 startIdx = input.IndexOf( "href=\"" );
if( startIdx < 0 ) return null;
Int32 endIdx = input.IndexOf( "\"", startIdx );
if( endIdx < 0 ) return null;
return input.Substring( startIdx, endIdx - startIdx );

I am sure you can find this elsewhere on Stack, but I would use string.split(). You can set up something similar to this...
public static void Main(){
char[] delimiterChars = { '"', ' ' };
string text = "<a href=\"https://genius.com/Run-the-jewels-lie-cheat-steal-lyrics\" class=\" song_link\" title=\"Lie, Cheat, Steal by Run the Jewels\">";
string[] words = text.Split(delimiterChars);
}
Assuming your tag is always structured the same, you will just need to grab the third string in the array to pull out the value you are looking for. You can also search for the index of href, and then split the string based on that, but this is how I would go about it.

Regex to remove this string in C#?

I am scripting Agent Jobs using SMO for SQL Server and the resulting script strings have a have parameter and value that I want to remove from the final version I am storing. The portion of the script that I want to look at is the schedule being added to the job, where it includes a #schedule_uid parameter with a GUID associated with it. I'd like to remove this entirely from the script.
EXEC #ReturnCode = msdb.dbo.sp_add_jobschedule #job_id=#jobId, #name='Job Name',
#enabled=1,
#freq_type=4,
#freq_interval=1,
#freq_subday_type=4,
#freq_subday_interval=10,
#freq_relative_interval=1,
#freq_recurrence_factor=0,
#active_start_date=20150119,
#active_end_date=99991231,
#active_start_time=0,
#active_end_time=235959,
#schedule_uid=N'a70709af-bce7-4c65-a4cd-7574acd31ca2'
The part that I want to replace is the following:
, \r\n\t\t#schedule_uid=N'a70709af-bce7-4c65-a4cd-7574acd31ca2'
So that the final string is:
EXEC #ReturnCode = msdb.dbo.sp_add_jobschedule #job_id=#jobId, #name='Job Name',
#enabled=1,
#freq_type=4,
#freq_interval=1,
#freq_subday_type=4,
#freq_subday_interval=10,
#freq_relative_interval=1,
#freq_recurrence_factor=0,
#active_start_date=20150119,
#active_end_date=99991231,
#active_start_time=0,
#active_end_time=235959
I've tried various combinations of things I've been reading online but I can't seem to make it replace or even match. I know that the regex for the guid matching is:
\b[A-F0-9]{8}(?:-[A-F0-9]{4}){3}-[A-F0-9]{12}\b'
I've tried to add this into a number of things, and thought that the following regex would work but can't figure out what I'm doing wrong or missing
#", \r\n\t\t#schedule_uid=N'\b[A-F0-9]{8}(?:-[A-F0-9]{4}){3}-[A-F0-9]{12}\b'"
#", \r\n\t\t#schedule_uid=N'[A-F0-9]{8}(?:-[A-F0-9]{4}){3}-[A-F0-9]{12}'"
#", \r\n\t\t\b#schedule_uid=N'[A-F0-9]{8}(?:-[A-F0-9]{4}){3}-[A-F0-9]{12}'\b"
I'm not looking for a solution as much as I'd like to know what I'm missing. I've been reading the regular-expressions.info site for a while and I'm usually able to figure out the correct regex, but this has had me stumped for a few days now.
EDIT:
It's not always the last item and it's not guaranteed to only occur once within the script since a job can have multiple schedules which have different #schedule_uid's and I want to get rid of all of them without looping. This is why I chose Regex for the operation. It also needs to remove the comma at the end of the previous parameters line for the code to remain syntax correct.

The following seems to work for me and it will enable you to remove all the newlines, tabs etc:
(?:\n|\t|\r|.){1,3}.*\#sc.*'
You can see it working here

There you go:
#schedule_uid=N'[\w]{8}-[\w]{4}-[\w]{4}-[\w]{4}-[\w]{12}'
Created and tested using http://regexpal.com/

Assuming as little as possible, just using basic string operations.
string exec = ...
int i = exec.IndexOf("#schedule_uid");
while (i > -1)
{
int j = i;
//Find the previous comma
while (exec[i] != ',')
i--;
//Find the end, next line, or next comma
while (j < exec.Length && exec[j] != '\r' && exec[j] != ',')
j++;
exec = exec.Remove(i, j - i);
i = exec.IndexOf("#schedule_uid");
}
I'm deliberately ignoring the no looping requirement, in favour of simple code that works. tested vs this...
string exec = #"
EXEC #ReturnCode = msdb.dbo.sp_add_jobschedule, #schedule_uid=N'a70709af-bce7-4c65-a4cd-7574acd31ca2', #job_id=#jobId, #name='Job Name',
#enabled=1,
#freq_type=4,
#freq_interval=1,
#freq_subday_type=4,
#freq_subday_interval=10,
#freq_relative_interval=1,
#freq_recurrence_factor=0,
#schedule_uid=N'a70709af-bce7-4c65-a4cd-7574acd31ca2',
#active_start_date=20150119,
#active_end_date=99991231,
#active_start_time=0,
#active_end_time=235959,
#schedule_uid=N'a70709af-bce7-4c65-a4cd-7574acd31ca2'";

A little more complicated, but works.
string test = "EXEC...";
var lines = test.Split(new char [] { ',' }).ToList();
lines = lines.Select((line, index) =>
{
var indexof = line.IndexOf("#schedule_uid");
if (indexof > -1)
{
if (index == 0)
{
return line.Substring(0, indexof);
}
else
{
return null;
}
}
return line + ",";
})
.Where(line => line != null)
.ToList();
test = string.Join(string.Empty, lines);
JsFiddle Example.

Character literal compile error

I downloaded a library to handle RTF. It won't compile. It fails on a character literal and I cannot figure out what it is.
The source is posted on SourceForge. The problem is in RtfNodeGroup.cs and it is at the end of the following code. myStr.Append( '¨C' );
When I look at the character sequence using od, it is ASCII '250 C'.
I know that there are two characters in the literal. This is how the code was posted on SourceForge. The block of code above the one in question failed also, but I substituted the literal for emdash as follows:
if( node.Keyword == "emdash")
{
AddString( myStr , buffer );
myStr.Append( '\u2014');
continue ;
}
What do you think it is?
else if( node.Type == RTFNodeType.Control || node.Type == RTFNodeType.Keyword )
{
if( node.Keyword == "tab" )
{
AddString( myStr , buffer );
myStr.Append( '\t' );
continue ;
}
if( node.Keyword == "emdash")
{
AddString( myStr , buffer );
myStr.Append( '¡ª');
continue ;
}
if( node.Keyword == "" )
{
AddString( myStr , buffer );
myStr.Append( '¨C' );
continue ;
}
}

I believe you're opening the file with the wrong encoding. It seems to be saved in UTF-8, while you're opening it in some form of ASCII+. Try to force the code file to be UTF-8, and it should work fine IMO.
EDIT: Okay, I actually downloaded the source and checked, and I believe that it might have been accidentally double encoded. If those are the only issues, just replace the string contents with the proper character (ideally using the \u2014 notation, which doesn't depend on code file encoding beyond ASCII).
FINAL EDIT: The name of the author tipped me off. The file is actually encoded in chinese (mainland) encoding (windows-936), not UTF-8. Convert the files to UTF-8 and you should be fine. In the proper encoding, ¡ª turns to — etc. The second one is actually –.

Regex to remove single-line SQL comments (--)

Question:
Can anybody give me a working regex expression (C#/VB.NET) that can remove single line comments from a SQL statement ?
I mean these comments:
-- This is a comment
not those
/* this is a comment */
because I already can handle the star comments.
I have a made a little parser that removes those comments when they are at the start of the line, but they can also be somewhere after code or worse, in a SQL-string 'hello --Test -- World'
Those comments should also be removed (except those in a SQL string of course - if possible).
Surprisingly I didn't got the regex working. I would have assumed the star comments to be more difficult, but actually, they aren't.
As per request, here my code to remove /**/-style comments
(In order to have it ignore SQL-Style strings, you have to subsitute strings with a uniqueidentifier (i used 4 concated), then apply the comment-removal, then apply string-backsubstitution.
static string RemoveCstyleComments(string strInput)
{
string strPattern = #"/[*][\w\d\s]+[*]/";
//strPattern = #"/\*.*?\*/"; // Doesn't work
//strPattern = "/\\*.*?\\*/"; // Doesn't work
//strPattern = #"/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+/ "; // Doesn't work
//strPattern = #"/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+/ "; // Doesn't work
// http://stackoverflow.com/questions/462843/improving-fixing-a-regex-for-c-style-block-comments
strPattern = #"/\*(?>(?:(?>[^*]+)|\*(?!/))*)\*/"; // Works !
string strOutput = System.Text.RegularExpressions.Regex.Replace(strInput, strPattern, string.Empty, System.Text.RegularExpressions.RegexOptions.Multiline);
Console.WriteLine(strOutput);
return strOutput;
} // End Function RemoveCstyleComments

I will disappoint all of you. This can't be done with regular expressions. Sure, it's easy to find comments not in a string (that even the OP could do), the real deal is comments in a string. There is a little hope of the look arounds, but that's still not enough. By telling that you have a preceding quote in a line won't guarantee anything. The only thing what guarantees you something is the oddity of quotes. Something you can't find with regular expression. So just simply go with non-regular-expression approach.
EDIT:
Here's the c# code:
String sql = "--this is a test\r\nselect stuff where substaff like '--this comment should stay' --this should be removed\r\n";
char[] quotes = { '\'', '"'};
int newCommentLiteral, lastCommentLiteral = 0;
while ((newCommentLiteral = sql.IndexOf("--", lastCommentLiteral)) != -1)
{
int countQuotes = sql.Substring(lastCommentLiteral, newCommentLiteral - lastCommentLiteral).Split(quotes).Length - 1;
if (countQuotes % 2 == 0) //this is a comment, since there's an even number of quotes preceding
{
int eol = sql.IndexOf("\r\n") + 2;
if (eol == -1)
eol = sql.Length; //no more newline, meaning end of the string
sql = sql.Remove(newCommentLiteral, eol - newCommentLiteral);
lastCommentLiteral = newCommentLiteral;
}
else //this is within a string, find string ending and moving to it
{
int singleQuote = sql.IndexOf("'", newCommentLiteral);
if (singleQuote == -1)
singleQuote = sql.Length;
int doubleQuote = sql.IndexOf('"', newCommentLiteral);
if (doubleQuote == -1)
doubleQuote = sql.Length;
lastCommentLiteral = Math.Min(singleQuote, doubleQuote) + 1;
//instead of finding the end of the string you could simply do += 2 but the program will become slightly slower
}
}
Console.WriteLine(sql);
What this does: find every comment literal. For each, check if it's within a comment or not, by counting the number of quotes between the current match and the last one. If this number is even, then it's a comment, thus remove it (find first end of line and remove whats between). If it's odd, this is within a string, find the end of the string and move to it. Rgis snippet is based on a wierd SQL trick: 'this" is a valid string. Even tho the 2 quotes differ. If it's not true for your SQL language, you should try a completely different approach. I'll write a program to that too if that's the case, but this one's faster and more straightforward.

You want something like this for the simple case
-{2,}.*
The -{2,} looks for a dash that happens 2 or more times
The .* gets the rest of the lines up to the newline
*But, for the edge cases, it appears that SinistraD is correct in that you cannot catch everything, however here is an article about how this can be done in C# with a combination of code and regex.

This seems to work well for me so far; it even ignores comments within strings, such as SELECT '--not a comment--' FROM ATable
private static string removeComments(string sql)
{
string pattern = #"(?<=^ ([^'""] |['][^']*['] |[""][^""]*[""])*) (--.*$|/\*(.|\n)*?\*/)";
return Regex.Replace(sql, pattern, "", RegexOptions.IgnorePatternWhitespace | RegexOptions.Multiline);
}
Note: it is designed to eliminate both /**/-style comments as well as -- style. Remove |/\*(.|\n)*?\*/ to get rid of the /**/ checking. Also be sure you are using the RegexOptions.IgnorePatternWhitespace Regex option!!
I wanted to be able to handle double-quotes too, but since T-SQL doesn't support them, you could get rid of |[""][^""]*[""] too.
Adapted from here.
Note (Mar 2015): In the end, I wound up using Antlr, a parser generator, for this project. There may have been some edge cases where the regex didn't work. In the end I was much more confident with the results having used Antlr, and it's worked well.

Using System.Text.RegularExpressions;
public static string RemoveSQLCommentCallback(Match SQLLineMatch)
{
System.Text.StringBuilder sb = new System.Text.StringBuilder();
bool open = false; //opening of SQL String found
char prev_ch = ' ';
foreach (char ch in SQLLineMatch.ToString())
{
if (ch == '\'')
{
open = !open;
}
else if ((!open && prev_ch == '-' && ch == '-'))
{
break;
}
sb.Append(ch);
prev_ch = ch;
}
return sb.ToString().Trim('-');
}
The code
public static void Main()
{
string sqlText = "WHERE DEPT_NAME LIKE '--Test--' AND START_DATE < SYSDATE -- Don't go over today";
//for every matching line call callback func
string result = Regex.Replace(sqlText, ".*--.*", RemoveSQLCommentCallback);
}
Let's replace, find all the lines that match dash dash comment and call your parsing function for every match.

As a late solution, the simplest way is to do it using ScriptDom-TSqlParser:
// https://michaeljswart.com/2014/04/removing-comments-from-sql/
// http://web.archive.org/web/*/https://michaeljswart.com/2014/04/removing-comments-from-sql/
public static string StripCommentsFromSQL(string SQL)
{
Microsoft.SqlServer.TransactSql.ScriptDom.TSql150Parser parser =
new Microsoft.SqlServer.TransactSql.ScriptDom.TSql150Parser(true);
System.Collections.Generic.IList<Microsoft.SqlServer.TransactSql.ScriptDom.ParseError> errors;
Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragment fragments =
parser.Parse(new System.IO.StringReader(SQL), out errors);
// clear comments
string result = string.Join(
string.Empty,
fragments.ScriptTokenStream
.Where(x => x.TokenType != Microsoft.SqlServer.TransactSql.ScriptDom.TSqlTokenType.MultilineComment)
.Where(x => x.TokenType != Microsoft.SqlServer.TransactSql.ScriptDom.TSqlTokenType.SingleLineComment)
.Select(x => x.Text));
return result;
}
or instead of using the Microsoft-Parser, you can use ANTL4 TSqlLexer
or without any parser at all:
private static System.Text.RegularExpressions.Regex everythingExceptNewLines =
new System.Text.RegularExpressions.Regex("[^\r\n]");
// http://drizin.io/Removing-comments-from-SQL-scripts/
// http://web.archive.org/web/*/http://drizin.io/Removing-comments-from-SQL-scripts/
public static string RemoveComments(string input, bool preservePositions, bool removeLiterals = false)
{
//based on http://stackoverflow.com/questions/3524317/regex-to-strip-line-comments-from-c-sharp/3524689#3524689
var lineComments = #"--(.*?)\r?\n";
var lineCommentsOnLastLine = #"--(.*?)$"; // because it's possible that there's no \r\n after the last line comment
// literals ('literals'), bracketedIdentifiers ([object]) and quotedIdentifiers ("object"), they follow the same structure:
// there's the start character, any consecutive pairs of closing characters are considered part of the literal/identifier, and then comes the closing character
var literals = #"('(('')|[^'])*')"; // 'John', 'O''malley''s', etc
var bracketedIdentifiers = #"\[((\]\])|[^\]])* \]"; // [object], [ % object]] ], etc
var quotedIdentifiers = #"(\""((\""\"")|[^""])*\"")"; // "object", "object[]", etc - when QUOTED_IDENTIFIER is set to ON, they are identifiers, else they are literals
//var blockComments = #"/\*(.*?)\*/"; //the original code was for C#, but Microsoft SQL allows a nested block comments // //https://msdn.microsoft.com/en-us/library/ms178623.aspx
//so we should use balancing groups // http://weblogs.asp.net/whaggard/377025
var nestedBlockComments = #"/\*
(?>
/\* (?<LEVEL>) # On opening push level
|
\*/ (?<-LEVEL>) # On closing pop level
|
(?! /\* | \*/ ) . # Match any char unless the opening and closing strings
)+ # /* or */ in the lookahead string
(?(LEVEL)(?!)) # If level exists then fail
\*/";
string noComments = System.Text.RegularExpressions.Regex.Replace(input,
nestedBlockComments + "|" + lineComments + "|" + lineCommentsOnLastLine + "|" + literals + "|" + bracketedIdentifiers + "|" + quotedIdentifiers,
me => {
if (me.Value.StartsWith("/*") && preservePositions)
return everythingExceptNewLines.Replace(me.Value, " "); // preserve positions and keep line-breaks // return new string(' ', me.Value.Length);
else if (me.Value.StartsWith("/*") && !preservePositions)
return "";
else if (me.Value.StartsWith("--") && preservePositions)
return everythingExceptNewLines.Replace(me.Value, " "); // preserve positions and keep line-breaks
else if (me.Value.StartsWith("--") && !preservePositions)
return everythingExceptNewLines.Replace(me.Value, ""); // preserve only line-breaks // Environment.NewLine;
else if (me.Value.StartsWith("[") || me.Value.StartsWith("\""))
return me.Value; // do not remove object identifiers ever
else if (!removeLiterals) // Keep the literal strings
return me.Value;
else if (removeLiterals && preservePositions) // remove literals, but preserving positions and line-breaks
{
var literalWithLineBreaks = everythingExceptNewLines.Replace(me.Value, " ");
return "'" + literalWithLineBreaks.Substring(1, literalWithLineBreaks.Length - 2) + "'";
}
else if (removeLiterals && !preservePositions) // wrap completely all literals
return "''";
else
throw new System.NotImplementedException();
},
System.Text.RegularExpressions.RegexOptions.Singleline | System.Text.RegularExpressions.RegexOptions.IgnorePatternWhitespace);
return noComments;
}

I don't know if C#/VB.net regex is special in some way but traditionally s/--.*// should work.

In PHP, i'm using this code to uncomment SQL (only single line):
$sqlComments = '#(([\'"`]).*?[^\\\]\2)|((?:\#|--).*?$)\s*|(?<=;)\s+#ms';
/* Commented version
$sqlComments = '#
(([\'"`]).*?[^\\\]\2) # $1 : Skip single & double quoted + backticked expressions
|((?:\#|--).*?$) # $3 : Match single line comments
\s* # Trim after comments
|(?<=;)\s+ # Trim after semi-colon
#msx';
*/
$uncommentedSQL = trim( preg_replace( $sqlComments, '$1', $sql ) );
preg_match_all( $sqlComments, $sql, $comments );
$extractedComments = array_filter( $comments[ 3 ] );
var_dump( $uncommentedSQL, $extractedComments );
To remove all comments see Regex to match MySQL comments

How do I trim the following string?

I have the string: "http://schemas.xmlsoap.org/ws/2004/09/transfer/Get". I want to trim everything from the last slash, so I just remain with "Get".

var s = "http://schemas.xmlsoap.org/ws/2004/09/transfer/Get";
s = s.Substring(s.LastIndexOf("/") + 1);

You could use the LastIndexOf method to get the position of the last / in the string and pass that into the Substring method as how many characters you want to trim off the string. That should leave you with the Get at the end.
[TestMethod]
public void ShouldResultInGet()
{
string url = "http://schemas.xmlsoap.org/ws/2004/09/transfer/Get";
int indexOfLastSlash = url.LastIndexOf( '/' ) + 1; //don't want to include the last /
Assert.AreEqual( "Get", url.Substring( indexOfLastSlash ) );
}

Use String.LastIndexOf to get the last forward slash
http://msdn.microsoft.com/en-us/library/ms224422.aspx

URI alternative if your using the well formed /Get /Put /Delete etc
var uri = new System.Uri("http://schemas.xmlsoap.org/ws/2004/09/transfer/Get");
string top = Path.GetFileName(uri.LocalPath);

try
int indexOfLastSlash = url.LastIndexOf( '/' ) + 1;
string s = url.Remove(0, indexOfLastSlash);
Assert.AreEqual( "Get", s );
this removes all data before & including the last '/'.
works fine here.