正确的时候匹配括号不应该

Question

With the input:

"a[href*=\\"test\\"]"

I am attempting to match the tag name from the following jQuery selector:

Regex r = new Regex("^[A-z]+");
string tagName = r.Match("a[href*=\"test\"]").Value;

The issue is that it collects the left bracket instead of just A through z:

tagName = "a[href"

Why would it collect the bracket if it was not specified in the expression?

Answer 1

It's because this

[A-z]

Creates a character range from ASCII 'A' to ASCII 'z'. There are characters other than letters between Z and a, one of them being the [ character. Use instead:

[A-Za-z]

To match the range from AZ and the range from az , but not the characters that fall in between them. You can look at an ASCII table to see the specifics, but the summary is that the characters (in their numerical ASCII order) look like this:

A, B, ..., Y, Z, [, \, ], ^, _, `, a, b, c, ..., z

Answer 2

You should try a tool like regexpal to test stuff like this. Here's your example:

http://regexpal.com/?flags=g&regex= ^%5BA-z%5D%2B&input=a%5Bhref*%3D%5C%22test%5C%22%5D

What's weird to me is the lower case "z" - for some reason, that is allowing the bracket to pass.

Try this:

^[^\[]+

http://regexpal.com/?flags=g&regex= ^%5B^%5C%5B%5D%2B&input=a%5Bhref*%3D%5C%22test%5C%22%5D