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Building a regular expression in C#

How to check the following text in C# with Regex:
key_in-get { 43243225543543543 };
or
key_in_set { password123 : 34980430943834 };
I tried to build a regular expression, but I failed after few hours.
Here is my code:
string text1 = "key_in-get { 322389238237 };";
string text2 = "key_in-set { password123 : 322389238237 };";
string pattern = "key_in-(get|set) { .* };";
var result1 = Regex.IsMatch(text, pattern);
Console.Write("Is valid: {0} ", result1);
var result2 = Regex.IsMatch(text, pattern);
Console.Write("Is valid: {0} ", result2);
I have to check if there is "set" or "get".
If the pattern finds "set" then it can only accept following pattern "text123 : 123456789", and if it finds "get" then should accept only "123456789".

You can use
key_in-(?:get|(set)) {(?(1) \w+ :) \w+ };
key_in-(?:get|(set))\s*{(?(1)\s*\w+\s*:)\s*\w+\s*};
key_in-(?:get|(set))\s*{(?(1)\s*\w+\s*:)\s*\d+\s*};
See the regex demo. The second one allows any amount of any whitespace between the elements and the third one allows only digits after : or as part of the get expression.
If the whole string must match, add ^ at the start and $ at the end of the pattern.
Details:
key_in- - a substring
(?:get|(set)) - get or set (the latter is captured into Group 1)
\s* - zero or more whitespaces
{ - a { char
(?(1)\s*\w+\s*:) - a conditional construct: if Group 1 matched, match one or more word chars enclosed with zero or more whitespaces and then a colon
\s*\w+\s* - one or more word chars enclosed with zero or more whitespaces
}; - a literal substring.

In the pattern that you tried key_in-(get|set) { .* }; you are matching either get or set followed by { until the last occurrence of } which could possibly also match key_in-get { }; };
As an alternative solution, you could use an alternation | specifying each of the accepted parts for the get and the set.
key_in-(?:get\s*{\s*\w+|set\s*{\s*\w+\s*:\s*\w+)\s*};
The pattern matches
key_in- Match literally
(?: Non capture group
get\s*{\s*\w+ Match get, { between optional whitespace chars and 1+ word chars
| Or
set\s*{\s*\w+\s*:\s*\w+ Match set, { between optional whitespace chars and word chars on either side with : in between.
) Close non capture group
\s*}; Match optional whitespace chars and };
Regex demo

how to get password from string "password is Rtt3Ved36" by regexp?

on condition that string may be is "password Rtt3Ved36" (without "is").
(?<=password\ is|password\ ).*
That regexp doesn't work, because always return "is Rtt3Ved36" (but i need "Rtt3Ved36"). How to keep order in OR condition?

You may use
password(?: is)?\s*(.*)
and grab Group 1 value.
See the regex demo.
Details
password - a literal substring
(?: is)? - an optional substring space + is
\s* - 0+ whitespace
(.*) - Group 1: any 0+ chars other than a newline.
In C#:
var m = Regex.Match(s, #"password(?: is)?\s*(.*)");
var result = string.Empty;
if (m.Success)
{
result = m.Groups[1].Value;
}

According to this site: https://regex101.com/ your regex does work and returns "Rtt3Ved36".

Matching a pattern in a string

I have a string
string str = "I am fine. How are you? You need exactly 4 pieces of sandwiches. Your ADAST Count is 5. Okay thank you ";
What I want is, get the ADAST count value. For the above example, it is 5.
The problem here is, the is after the ADAST Count. It can be is or =. But there will the two words ADAST Count.
What I have tried is
var resultString = Regex.Match(str, #"ADAST\s+count\s+is\s+\d+", RegexOptions.IgnoreCase).Value;
var number = Regex.Match(resultString, #"\d+").Value;
How can I write the pattern which will search is or = ?

You may use
ADAST\s+count\s+(?:is|=)\s+(\d+)
See the regex demo
Note that (?:is|=) is a non-capturing group (i.e. it is used to only group alternations without pushing these submatches on to the capture stack for further retrieval) and | is an alternation operator.
Details:
ADAST - a literal string
\s+ - 1 or more whitespaces
count - a literal string
\s+ - 1 or more whitespaces
(?:is|=) - either is or =
\s+ - 1 or more whitespaces
(\d+) - Group 1 capturing one or more digits
C#:
var m = Regex.Match(s, #"ADAST\s+count\s+(?:is|=)\s+(\d+)", RegexOptions.IgnoreCase);
if (m.Success) {
Console.Write(m.Groups[1].Value);
}

Regular expression matching a given structure

I need to generate a regex to match any string with this structure:
{"anyWord"}{"aSpace"}{"-"}{"anyLetter"}
How can I do it?
Thanks
EDIT
I have tried:
string txt="print -c";
string re1="((?:[a-z][a-z]+))"; // Word 1
Regex r = new Regex(re1,RegexOptions.IgnoreCase|RegexOptions.Singleline);
Match m = r.Match(txt);
if (m.Success)
{
String word1=m.Groups[1].ToString();
Console.Write("("+word1.ToString()+")"+"\n");
}
Console.ReadLine();
but this only matches the word "print"

This would be pretty straight-forward :
[a-zA-Z]+\s\-[a-zA-Z]
explained as follows :
[a-zA-Z]+ # Matches 1 or more letters
\s # Matches a single space
\- # Matches a single hyphen / dash
[a-zA-Z] # Matches a single letter
If you needed to implement this in C#, you could just use the Regex class and specifically the Regex.Matches() method:
var matches = Regex.Matches(yourString,#"[a-zA-Z]+\s\-[a-zA-Z]");
Some example matching might look like this :

search string for everything before a set of characters in C#

I'm looking for a way to search a string for everything before a set of characters in C#. For Example, if this is my string value:
This is is a test.... 12345
I want build a new string with all of the characters before "12345".
So my new string would equal "This is is a test.... "
Is there a way to do this?
I've found Regex examples where you can focus on one character but not a sequence of characters.

You don't need to use a Regex:
public string GetBitBefore(string text, string end)
{
var index = text.IndexOf(end);
if (index == -1) return text;
return text.Substring(0, index);
}

You can use a lazy quantifier to match anything, followed by a lookahead:
var match = Regex.Match("This is is a test.... 12345", #".*?(?=\d{5})");
where:
.*? lazily matches everything (up to the lookahead)
(?=…) is a positive lookahead: the pattern must be matched, but is not included in the result
\d{5} matches exactly five digits. I'm assuming this is your lookahead; you can replace it

You can do so with help of regex lookahead.
.*(?=12345)
Example:
var data = "This is is a test.... 12345";
var rxStr = ".*(?=12345)";
var rx = new System.Text.RegularExpressions.Regex (rxStr,
System.Text.RegularExpressions.RegexOptions.IgnoreCase);
var match = rx.Match(data);
if (match.Success) {
Console.WriteLine (match.Value);
}
Above code snippet will print every thing upto 12345:
This is is a test....
For more detail about see regex positive lookahead

This should get you started:
var reg = new Regex("^(.+)12345$");
var match = reg.Match("This is is a test.... 12345");
var group = match.Groups[1]; // This is is a test....
Of course you'd want to do some additional validation, but this is the basic idea.

^ means start of string
$ means end of string
The asterisk tells the engine to attempt to match the preceding token zero or more times. The plus tells the engine to attempt to match the preceding token once or more
{min,max} indicate the minimum/maximum number of matches.
\d matches a single character that is a digit, \w matches a "word character" (alphanumeric characters plus underscore), and \s matches a whitespace character (includes tabs and line breaks).
[^a] means not so exclude a
The dot matches a single character, except line break characters
In your case there many way to accomplish the task.
Eg excluding digit: ^[^\d]*
If you know the set of characters and they are not only digit, don't use regex but IndexOf(). If you know the separator between first and second part as "..." you can use Split()

Take a look at this snippet:
class Program
{
static void Main(string[] args)
{
string input = "This is is a test.... 12345";
// Here we call Regex.Match.
MatchCollection matches = Regex.Matches(input, #"(?<MySentence>(\w+\s*)*)(?<MyNumberPart>\d*)");
foreach (Match item in matches)
{
Console.WriteLine(item.Groups["MySentence"]);
Console.WriteLine("******");
Console.WriteLine(item.Groups["MyNumberPart"]);
}
Console.ReadKey();
}
}

You could just split, not as optimal as the indexOf solution
string value = "oiasjdoiasj12345";
string end = "12345";
string result = value.Split(new string[] { end }, StringSplitOptions.None)[0] //Take first part of the result, not the quickest but fairly simple