所需标签的正则表达式模式

Question

Howzit,

I need help with the following please.

I need to find tags in a string. These tags start with {{ and end with }} , there will be multiple tags in the string I receive.

So far I have this, but it doesn't find any matches, what am I missing here?

List<string> list = new List<string>();

string pattern = "{{*}}";

Regex r = new Regex(pattern, RegexOptions.IgnoreCase);
Match m = r.Match(text);

while (m.Success)
{
    list.Add(m.Groups[0].Value);

    m = m.NextMatch();
}


return list;

even tried string pattern = "{{[A-Za-z0-9]}}"; thanx

PS. I know close to nothing about regex.

Answer 1

Not only do you want to use {{.+?}} as your regex, you also need to pass RegexOptions.SingleLine. That will treat your entire string as a single line and the . will match \\n (which it normally will not do).

Answer 2

Try {{.+}} . The .+ means there has to be at least one character as part of the tag.

EDIT:

To capture the string containing your tags you can do {{(.+)}} and then tokenize your match with the Tokenize or Scanner class?

Answer 3

I would recommend trying something like the following:

List<string> list = new List<string>();

string pattern = "{{(.*?)}}";

Regex r = new Regex(pattern, RegexOptions.IgnoreCase);
Match m = r.Match(text);

while (m.Success)
{
    list.Add(m.Groups[1].Value);

    m = m.NextMatch();
}

return list;

the regex specifies:

{{       # match {{ literally
(        # begin capturing into group #1
  .*?    # match any characters, from zero to infinite, but be lazy*
)        # end capturing group
}}       # match }} literally

"lazy" means to attempt to continue matching the pattern afterwards " }} " before backtracking to the .*? and reluctantly adding a character to the capturing group only if the character does not match }} - hope that made sense.

I changed your code by modifying the regex and to extract the first matching group from the regex match object ( m.Groups[1].value ) instead of the entire match.

Answer 4

{{.*?}} or {{.+?}}

. - means any symbol

? - means lazy(don't capute nextpattern)