查找电子邮件地址与网址

Real text is full of structured snippets like emails and links. Regex lets you pull these out automatically, even from long, messy documents.

An email has a name, an at sign, a domain, and an extension. Spotting that shape is the first step to writing a pattern for it.

This email pattern grabs word characters, an at sign, more characters, a dot, and letters. It is not perfect, but it catches most real addresses.

In a domain you want a literal dot, not the any-character dot. So you escape it as \. to match only a real period in the address.

Pair your email pattern with re.findall to sweep an entire document and return every address it contains as a clean Python list.

A URL usually starts with http or https, then ://, then a domain and path. That predictable start makes it a great target for regex.

This URL pattern matches http or https, then any non-space characters. The optional s after http is written with a question mark quantifier.

The question mark makes the part before it optional. In https? the s may or may not be there, so both http and https match cleanly.

By default quantifiers are greedy and grab as much as they can. With URLs this can swallow trailing punctuation you did not want.

Use \S to stop at the first space, or trim the result afterward. Knowing where a match should end keeps your extraction tidy.

Always test your pattern on messy real text. Edge cases like plus signs in emails or query strings in URLs reveal where it still leaks.

You want http to be optional in the s only. Which symbol makes the preceding character optional?

You built patterns for emails and URLs, escaped literal dots, and used the question mark for optional parts. Now you can mine contact info from text. 🔍