正则表达式设置单词字符并匹配确切的单词

Question

I need my C# regex to only match full words, and I need to make sure that +-/*() delimit words as well (I'm not sure if the last part is already set that way.) I find regexes very confusing and would like some help on the matter. Currently, my regex is:

public Regex codeFunctions = new Regex("draw_line|draw_rectangle|draw_circle");

Thank you! :)

Answer 1

Try

public Regex codeFunctions = new Regex(@"\b(draw_line|draw_rectangle|draw_circle)\b");

The \\b means match a word boundary, ie a transition from a non-word character to a word character (or vice versa).

Word characters include alphabet characters, digits, and the underscore symbol. Non-word characters include everything else, including +-/*() , so it should work fine for you.

See the Regex Class documentation for more details.

The @ at the start of the string makes the string a verbatim string , otherwise you have to type two backslashes to make one backslash.

Answer 2

Do you want to match any words, or just the words listed above? To match an arbitrary word, substitute this for the bit that creates the Regex object:

new Regex (@"\b(\w+)\b");

In the future, if you want more characters to be treated as whitespace (for example, underscores), I would recommend String.Replace-ing them to a space character. There may be a clever way to get the same effect with regular expressions, but personally I think it would be too clever. The String.Replace version is obvious.

Also, I can't help but recommend that you read up on regular expressions. Yes, they look like line noise until you get used to them, but once you do they're convenient and there are plenty of good resources out there to help you.