Question

I’m trying to make a Regular Expression in C# that will match strings like"�", but my Regex stops at the first match, and I’d like to match the whole string.

I’ve been trying with a lot of ways to do this, currently, my code looks like this:

string sPattern = @"/&#\d{2};/";
Regex rExp = new Regex(sPattern);
MatchCollection mcMatches = rExp.Matches(txtInput.Text);
foreach (Match m in mcMatches) {
    if (!m.Success) {
        //Give Warning
    }
}

And also tried lblDebug.Text = Regex.IsMatch(txtInput.Text, "(&#[0-9]{2};)+").ToString(); but it also only finds the first match.

Any tips?

Edit:

The end result I’m seeking is that strings like �&# are labeled as incorrect, as it is now, since only the first match is made, my code marks this as a correct string.

Second Edit:

I changed my code to this

string sPattern = @"&#\d{2};";
Regex rExp = new Regex(sPattern);

MatchCollection mcMatches = rExp.Matches(txtInput.Text);
int iMatchCount = 0;
foreach (Match m in mcMatches) {
    if (m.Success) {
        iMatchCount++;
    }
}

int iTotalStrings = txtInput.Text.Length / 5;
int iVerify = txtInput.Text.Length % 5;

if (iTotalStrings == iMatchCount && iVerify == 0) {
    lblDebug.Text = "True";
} else {
    lblDebug.Text = "False";
}

And this works the way I expected, but I still think this can be achieved in a better way.

Third Edit:
As @devundef suggest, the expression "^(&#\d{2};)+$" does the work I was hopping, so with this, my final code looks like this:

string sPattern = @"^(&#\d{2};)+$";
Regex rExp = new Regex(sPattern);
lblDebug.Text = rExp.IsMatch(txtInput.Text).ToString();

I always neglect the start and end of string characters (^ / $).

Answer 1

Remove the / at the start and end of the expression.

string sPattern = @"&#\d{2};";

EDIT

I tested the pattern and it works as expected. Not sure what you want.

Two options:

&#\d{2}; => will give N matches in the string. On the string � it will match 2 groups, � and 

(&#\d{2};)+ => will macth the whole string as one single group. On the string � it will match 1 group, �

Edit 2:

What you want is not get the groups but know if the string is in the right format. This is the pattern:

Regex rExp = new Regex(@"^(&#\d{2};)+$");

var isValid = rExp.IsMatch("�") // isValid = true
var isValid = rExp.IsMatch("�xyz") // isValid = false