求匹配无首尾空格且含多连续空格字符串的Regex

Perfect, I've got a regex that meets your exact needs, plus a breakdown of how it works and examples to test against.

The Regex #

^(?!\s)(?=.*\s{2,})(?!.*\s$).+$

Breakdown of Each Part #

Let's unpack what each segment does to ensure it hits all your rules:

• ^(?!\s): Negative lookahead at start — guarantees the string doesn't begin with any whitespace character.
• (?=.*\s{2,}): Positive lookahead — checks that somewhere in the string, there's at least one pair of consecutive spaces (\s{2,} matches 2+ spaces, so this covers 2, 3, or more in a row).
• (?!.*\s$): Negative lookahead at end — makes sure the string doesn't end with whitespace.
• .+$: Matches one or more non-newline characters, so we don't match empty strings.

Valid Test Cases (Regex Returns True) #

• "hello world" (two consecutive spaces in the middle; no leading/trailing spaces)
• "foo bar baz" (three consecutive spaces between "foo" and "bar")
• "a b c d" (multiple sets of consecutive spaces throughout)
• "test123 456test" (consecutive spaces between numeric and alphabetic characters)

Invalid Test Cases (Regex Returns False) #

• " hello world" (starts with a space)
• "hello world " (ends with a space)
• "hello world" (only single spaces, no consecutive duplicates)
• " hello world " (leading and trailing spaces present)
• "" (empty string)
• "singleword" (no spaces at all)

内容的提问来源于stack exchange，提问作者Saad