I have a list of string taken from a file. Some of this strings are in the format "Q" + number + "null" (e.g. Q98null, Q1null, Q24null, etc)
With a foreach loop I must check if a string is just like the one shown before. I use this right now
string a = "Q9null" //just for testing
if(a.Contains("Q") && a.Contains("null"))
MessageBox.Show("ok");
but I'd like to know if there is a better way to do this with regex. Thank you!
Your method will produce a lot of false positives - for example, it would recognize some invalid strings, such as "nullQ" or "Questionable nullability".
A regex to test for the match would be "^Q\\d+null$". The structure is very simple: it says that the target string must start in a Q, then one or more decimal digits should come, and then there should be null at the end.
Console.WriteLine(Regex.IsMatch("Q123null", "^Q\\d+null$")); // Prints True
Console.WriteLine(Regex.IsMatch("nullQ", "^Q\\d+null$")); // Prints False
public static bool Check(string s)
{
Regex regex = new Regex(@"^Q\d+null$");
Match match = regex.Match(s);
return match.Success;
}
Apply the above method in your code:
string a = "Q9null" //just for testing
if(Check(a))
MessageBox.Show("ok");
First way: Using the Regex
Use this Regex ^Q\d+null$
Second way: Using the SubString
string s = "Q1123null";
string First,Second,Third;
First = s[0].ToString();
Second = s.Substring(1,s.Length-5);
Third = s.Substring(s.Length-4);
Console.WriteLine (First);
Console.WriteLine (Second);
Console.WriteLine (Third);
then you can check everything after this...
