C# Regex trying to understand the logic - regex

Question

I'm starving to understand the logic of regex let's say I got this string
1 SM-TEST S/M-BLEU, 25.00 EA 96.00
private void Window_Loaded(object sender, RoutedEventArgs e)
{
var test = ReadPdfFile("C:\\Users\\mducharme\\Desktop\\PO # 70882.pdf");
var result = Regex.Split(test, "\r\n|\r|\n");
foreach (var lines in result)
{
if (Regex.IsMatch(lines, #"^\d\s"))
{
string line = lines.ToString();
string pattern = #"^(\S+\s+\S+).*?,(?=\s*\d+\.\d+\b)";
string replacement = "$1";
string result2 = Regex.Replace(line, pattern, replacement);
System.Diagnostics.Debug.WriteLine(result2);
}
}
}
Each lines show a different value like the first one and so on
2 SM-BLABLA S-M-YELLOW, 50.00 EA 96.00...
In the end I want to show up in my MessageBox for the first value only
1 SM-TEST 25.00 EA 96.00
but the regex doesn't seems to do it's job compared to regex101 website code.
Thank you,

Answer 1

Use
^(\d+\s+(?:(?!\d+\.\d+\s+[xX]\s+\d+\.\d+)[A-Z0-9-])+).*?(?=\s\d+\.\d+\s)
See regex proof. Replace with $1.
EXPLANATION
--------------------------------------------------------------------------------
^ the beginning of the string
--------------------------------------------------------------------------------
( group and capture to \1:
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times (matching
the most amount possible))
--------------------------------------------------------------------------------
\s+ whitespace (\n, \r, \t, \f, and " ") (1
or more times (matching the most amount
possible))
--------------------------------------------------------------------------------
(?: group, but do not capture (1 or more
times (matching the most amount
possible)):
--------------------------------------------------------------------------------
(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
\. '.'
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
\s+ whitespace (\n, \r, \t, \f, and " ")
(1 or more times (matching the most
amount possible))
--------------------------------------------------------------------------------
[xX] any character of: 'x', 'X'
--------------------------------------------------------------------------------
\s+ whitespace (\n, \r, \t, \f, and " ")
(1 or more times (matching the most
amount possible))
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
\. '.'
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times
(matching the most amount possible))
--------------------------------------------------------------------------------
) end of look-ahead
--------------------------------------------------------------------------------
[A-Z0-9-] any character of: 'A' to 'Z', '0' to
'9', '-'
--------------------------------------------------------------------------------
)+ end of grouping
--------------------------------------------------------------------------------
) end of \1
--------------------------------------------------------------------------------
.*? any character except \n (0 or more times
(matching the least amount possible))
--------------------------------------------------------------------------------
(?= look ahead to see if there is:
--------------------------------------------------------------------------------
\s whitespace (\n, \r, \t, \f, and " ")
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times (matching
the most amount possible))
--------------------------------------------------------------------------------
\. '.'
--------------------------------------------------------------------------------
\d+ digits (0-9) (1 or more times (matching
the most amount possible))
--------------------------------------------------------------------------------
\s whitespace (\n, \r, \t, \f, and " ")
--------------------------------------------------------------------------------
) end of look-ahead