正则表达式只匹配引号内的空格

Question

I need to match any space within double quotes ONLY - not outside. I've tried a few things, but none of them work.

• [^"]\\s[^"] - matches spaces outside of quotes
• [^"] [^"] - see above
• \\s+ - see above

For example I want to match "hello world" but not "helloworld" and not hello world (without quotes). I will specifically be using this regex inside of Visual Studio via the Find feature.

Answer 1

With .net and pcre regex engines, you can use the \\G feature that matches the position after a successful match or the start of the string to build a pattern that returns contiguous occurrences from the start of the string:

((?:\G(?!\A)|\A[^"]*")[^\s"]*)\s([^\s"]*"[^"]*")?

example for a replacement with #: demo

pattern details:

( # capture group 1
    (?: # two possible beginning
        \G(?!\A) # contiguous to a previous match
      |          # OR
        \A[^"]*" # start of the string and reach the first quote
    )   # at this point you are sure to be inside quotes    
    [^\s"]* # all that isn't a white-space or a quote
)
\s # the white-space
([^\s"]*"[^"]*")? # optional capture group 2: useful for the last quoted white-space
                  # since it reaches an eventual next quoted part. 

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Notice: with the .net regex engine you can also use the lookbehind to test if the number of quotes before a space is even or odd, but this way isn't efficient. (same thing for a lookahead that checks remaining quotes until the end, but in addition this approach may be wrong if the quotes aren't balanced).