正则表达式模式可根据“起始于”和“出现次数”来匹配字符串

Question

I need to find out only URLs those starts with http://www.example.com/blog/ and total number of character / is exactly 5 .

So it won't matches URL like

http://www.example.com/blog/category/cat-1/
http://www.example.com/blog/category/cat-2/
http://www.example.com/blog/tags/a-b-c/

It should only match URLs like

http://www.example.com/blog/a-blog-title/
http://www.example.com/blog/another-blog-title/
http://www.example.com/blog/just-one-more-blog-title/

I have tried a lot on regxr but could not create one.

I will implement it in C# (if it makes any different).

Thanks in advance.

Answer 1

You want something like:

bool isMatch = Regex.IsMatch(str, "^http://www.example.com/blog/[^/]*/[^/]*$");

(starts with your url, has 0-n characters, followed by a /, followed by 0-n characters, end of the string)

Answer 2

这应该可以解决问题：

Regex reg = new Regex(@"^http://www.example.com/blog/[^/]*/[^/]*/$");

Answer 3

For this kind of task i'd use the Uri class instead, for example (tested with a text file):

Uri uri = null;
var uris = File.ReadLines(filePath)
    .Where(l => Uri.TryCreate(l.Trim(), UriKind.Absolute, out uri))
    .Select(l => uri);

var validUris = uris
    .Where(u => u.Host == "www.example.com"
             && u.Segments.Length == 3
             && u.Segments[1] == "blog/");

Answer 4

You could try something like

^http://(?=www.example.com/blog/)([^/]*/){3}$

Would match any url that starts with www.example.com/blog/ (after the http:// bit) and has a total of 5, two in the http:// and 3 in whatever comes after.

Not very well versed in C# so I'm not sure how to best apply the expression however.