正则表达式的第一个数字出现

Question

My task is extract the first digits in the following string:

GLB=VSCA|34|speed|1|

My pattern is the following:

(?x:VSCA(\|){1}(\d.))

Basically I need to extract "34", the first digits occurrence after the "VSCA". With my pattern I obtain a group but would be possibile to get only the number? this is my c# snippet:

string regex = @"(?x:VSCA(\|){1}(\d.))";
Regex rx = new Regex(regex);
string s = "GLB=VSCA|34|speed|1|";

if (rx.Match(s).Success)
{
    var test = rx.Match(s).Groups[1].ToString();
}

Answer 1

You could match 34 (the first digits after VSCA ) using a positive lookbehind (?<=VSCA\\D*) to assert that what is on the left side is VSCA followed by zero or times not a digit \\D* and then match one or more digits \\d+ :

(?<=VSCA\\D*)\\d+

If you need the pipe to be after VSCA the you could include that in the lookbehind:

(?<=VSCA\\|)\\d+

Demo

Answer 2

This regex pattern: (?<=VSCA\\|)\\d+?(?=\\|) will match only the number. (If your number can be negative / have decimal places you may want to use (?<=VSCA\\|).+?(?=\\|) instead)

Answer 3

You don't need Regex for this, you can simply split on the '|' character:

string s = "GLB=VSCA|34|speed|1|";

string[] parts = s.Split('|');

if(parts.Length >= 2)
{
    Console.WriteLine(parts[1]); //prints 34
}

The benefit here is that you can access all parts of the original string based on the index:

[0] - "GLB=VSCA"
[1] - "34"
[2] - "speed"
[3] - "1"

Fiddle here

Answer 4

While the other answers work really well, if you really must use a regular expression, or are interested in knowing how to get to that straight away you can use a named group for the number. Consider the following code:

string regex = @"(?x:VSCA(\|){1}(?<number>\d.?))";
Regex rx = new Regex(regex);
string s = "GLB:VSCA|34|speed|1|";

var match = rx.Match(s); 
if(match.Success) Console.WriteLine(match.Groups["number"]);

Answer 5

How about (?<=VSCA\\|)[0-9]+ ?

Try it out here