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schemeracketwhitespace

Check if a string is empty or only whitespace characters in racket

How do I check if a string is empty or all whitespace characters in racket? the example on their site (string$?) doesn't work

Solution

  • Use regexp-match-exact? with this regex: #px"\\s*", which matches whitespace character zero or more times:

    > (regexp-match-exact? #px"\\s*" "a")
#f
> (regexp-match-exact? #px"\\s*" "")
#t
> (regexp-match-exact? #px"\\s*" "    ")
#t
> (regexp-match-exact? #px"\\s*" "
")
#t

    non-empty-string? has different results for empty string and string with whitespace characters:

    > (non-empty-string? "  ")
#t
> (non-empty-string? "")
#f